Advanced oxidation process for ex-situ groundwater remediation

ABSTRACT

Methods of treating contaminated groundwater having recalcitrant organic contaminants are disclosed. The methods include pretreating the contaminated groundwater to remove iron, introducing a persulfate to the contaminated groundwater, and exposing the contaminated groundwater to irradiation. The methods may also include extracting the contaminated groundwater from a feed stream. The methods may also include preparing the persulfate with high purity water. Systems for treating contaminated groundwater having recalcitrant organic contaminants are also disclosed. The systems include a pretreatment subsystem, a source of persulfate, and an irradiation source.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part of U.S. patent applicationSer. No. 15/002,474, titled “ADVANCED OXIDATION PROCESS FOR EX-SITUGROUNDWATER REMEDIATION” filed Jan. 21, 2016, which claims priorityunder 35 U. S. C. § 119(e) to U.S. Provisional Application Ser. No.62/105,811, titled “ADVANCED OXIDATION PROCESS FOR EX-SITU GROUNDWATERREMEDIATION,” filed Jan. 21, 2015 and is related to commonly owned U.S.Provisional Application Ser. No. 62/203,644, titled “DESTRUCTION OFTRACE ORGANIC CONTAMINANTS USING AN ADVANCED OXIDATION PROCESS,” filedAug. 11, 2015. This application also claims priority under 35 U. S. C. §119(e) to U.S. Provisional Application Ser. No. 62/644,058, titled“ADVANCED OXIDATION PROCESS FOR EX-SITU GROUNDWATER REMEDIATION,” filedMar. 16, 2018. Each of these applications is incorporated herein byreference in its entirety for all purposes.

SUMMARY

In accordance with one aspect, there is provided a method of treatingcontaminated groundwater having an initial concentration of arecalcitrant organic contaminant and an initial concentration of iron.The method may comprise pretreating the contaminated groundwater toproduce a pretreated groundwater having a concentration of iron lessthan the initial concentration of iron. The method may compriseintroducing a persulfate to the pretreated groundwater to produce afirst treated aqueous solution. The method may comprise exposing thefirst treated aqueous solution to irradiation to produce a secondtreated aqueous solution. The second treated aqueous solution may have aconcentration of the recalcitrant organic contaminant that is at least50% less than the initial concentration of recalcitrant organiccontaminant.

In some embodiments, pretreating the contaminated groundwater maycomprise at least one of oxidizing the contaminated groundwater andtreating the contaminated groundwater with a filtration media. Themethod may comprise introducing a source of chlorine or an oxygencontaining gas to the contaminated groundwater. The method may comprisetreating the contaminated groundwater with the filtration media selectedfrom manganese dioxide, manganese oxide, and silica.

In some embodiments, the concentration of iron in the pretreatedgroundwater may be less than a concentration sufficient to deactivatethe persulfate. For instance, the concentration of iron in thepretreated groundwater may be 0.1 mg/L or less.

The method may further comprise recirculating at least a portion of thesecond treated aqueous solution to a point upstream from theintroduction of the persulfate.

In accordance with certain embodiments, the concentration ofrecalcitrant organic contaminant in the second treated aqueous solutionmay be at least 99% less than the initial concentration of contaminant.The recalcitrant organic contaminant may be 1,4-dioxane. Theconcentration of the recalcitrant organic contaminant in the secondtreated aqueous solution may be 1 ppb or less.

In some embodiments, the second treated aqueous solution may be potablewater. In some embodiments, the method may comprise extracting thecontaminated groundwater from a remediation site.

The recalcitrant organic contaminant may be selected from 1,4-dioxane,trichloroethylene (TCE), perchloroethylene (PCE), urea, isopropanol,chloroform, atrazine, tryptophan, and formic acid.

The method may further comprise measuring a total organic carbon (TOC)value of the contaminated groundwater to be treated. The method mayfurther comprise adjusting at least one of a rate at which thepersulfate is introduced to the contaminated groundwater and a dose ofthe irradiation based on the measured TOC value.

In some embodiments, the irradiation may be produced by an ultravioletlamp. The method may comprise cleaning the ultraviolet lamp.

In accordance with another aspect, there is provided a method oftreating contaminated groundwater having an initial concentration of arecalcitrant organic contaminant. The method may comprise extracting thecontaminated groundwater from a feed stream. The method may comprisepreparing an aqueous persulfate solution with high purity water. Themethod may comprise introducing the aqueous persulfate solution to theextracted groundwater to produce a first treated aqueous solution. Themethod may comprise exposing the first treated aqueous solution toirradiation to produce a second treated aqueous solution. The secondtreated aqueous solution may have a concentration of the recalcitrantorganic contaminant that is at least 50% less than the initialconcentration of recalcitrant organic contaminant.

In some embodiments, the aqueous persulfate solution may be preparedwith deionized water or reverse osmosis permeate.

The method may comprise pretreating the extracted groundwater to removeiron before introducing the aqueous persulfate solution. In someembodiments, pretreating the extracted groundwater comprises at leastone of oxidizing the extracted groundwater and filtering the extractedgroundwater with a media filter. In some embodiments, a concentration ofiron in the pretreated groundwater may be 0.1 mg/L or less.

The recalcitrant organic contaminant may be selected from 1,4-dioxane,trichloroethylene (TCE), perchloroethylene (PCE), urea, isopropanol,chloroform, atrazine, tryptophan, and formic acid. In some embodiments,the recalcitrant organic contaminant may be 1,4-dioxane. Theconcentration of the recalcitrant organic contaminant in the secondtreated aqueous solution may be 5 ppb or less.

The method may further comprise measuring a total organic carbon (TOC)value of the contaminated groundwater to be treated. In someembodiments, the method may further comprise adjusting at least one of arate at which the persulfate is introduced to the contaminatedgroundwater and a dose of the irradiation based on the measured TOCvalue.

In some embodiments, the irradiation may be produced by an ultravioletlamp. The method may comprise cleaning the ultraviolet lamp.

In accordance with yet another aspect, there is provided a system fortreating contaminated groundwater. The system may comprise apretreatment subsystem capable of removing iron from an aqueoussolution. The system may comprise a source of persulfate fluidlyconnectable to a source of contaminated groundwater having an initialconcentration of a recalcitrant organic contaminant. The source ofpersulfate may be fluidly connected downstream from the pretreatmentsubsystem. The source of persulfate may be configured to introduce thepersulfate to the contaminated groundwater and produce a first treatedaqueous solution. The system may comprise an irradiation source fluidlyconnected downstream from the source of persulfate. The irradiationsource may be configured to irradiate the contaminated groundwater andproduce a second treated aqueous solution having a concentration of therecalcitrant organic contaminant lower than the initial concentration ofthe recalcitrant organic contaminant.

In some embodiments, the pretreatment subsystem may be fluidlyconnectable downstream from the source of contaminated groundwater. Thepretreatment subsystem may be configured to remove iron from thecontaminated groundwater. The pretreatment subsystem may comprise amedia filter. The media filter may comprise filtration media selectedfrom manganese dioxide, manganese oxide, and silica. The pretreatmentsubsystem may comprise a source of an oxidant. The source of the oxidantmay comprise chlorine, permanganate, or an oxygen containing gas.

The pretreatment subsystem may comprise a water purification unit. Thepretreatment subsystem may be configured to produce high purity waterfor the source of persulfate. The water purification unit may comprisean ion exchange unit or a reverse osmosis unit.

The system may further comprise a TOC concentration sensor fluidlyconnected to the contaminated groundwater. The system may furthercomprise a controller operably connected to the TOC concentrationsensor. The controller may be configured to control at least one of arate at which the persulfate is introduced to the contaminatedgroundwater and a dose of irradiation applied by the irradiation sourcebased on an output signal from the TOC concentration sensor.

The system may be a mobile-based platform.

In some embodiments, the system may comprise a pump configured toextract the contaminated groundwater from the source of contaminatedgroundwater. The source of contaminated groundwater may be a remediationsite.

The irradiation source may be configured to produce the second treatedaqueous solution having a concentration of the recalcitrant organiccontaminant that is at least 50% less than the initial concentration ofrecalcitrant organic contaminant. The irradiation source may beconfigured to produce the second treated aqueous solution having aconcentration of the recalcitrant organic contaminant that is at least99% less than the initial concentration of recalcitrant organiccontaminant. The recalcitrant organic contaminant may be 1,4-dioxane andthe irradiation source may be configured to produce the second treatedaqueous solution having a concentration of the recalcitrant organiccontaminant of 1 ppb or less.

In accordance with certain embodiments, the system may further comprisea recirculation line extending between a point downstream from theirradiation source and a point upstream from the source of persulfate.In some embodiments, the point upstream from the source of persulfatemay be upstream from the pretreatment subsystem.

Still other aspects, embodiments, and advantages of these exampleaspects and embodiments, are discussed in detail below. Moreover, it isto be understood that both the foregoing information and the followingdetailed description are merely illustrative examples of various aspectsand embodiments, and are intended to provide an overview or frameworkfor understanding the nature and character of the claimed aspects andembodiments. Embodiments disclosed herein may be combined with otherembodiments, and references to “an embodiment,” “an example,” “someembodiments,” “some examples,” “an alternate embodiment,” “variousembodiments,” “one embodiment,” “at least one embodiment,” “this andother embodiments,” “certain embodiments,” or the like are notnecessarily mutually exclusive and are intended to indicate that aparticular feature, structure, or characteristic described may beincluded in at least one embodiment. The appearances of such termsherein are not necessarily all referring to the same embodiment.

BRIEF DESCRIPTION OF DRAWINGS

Various aspects of at least one embodiment are discussed below withreference to the accompanying figures, which are not intended to bedrawn to scale. The figures are included to provide an illustration anda further understanding of the various aspects and embodiments, and areincorporated in and constitute a part of this specification, but are notintended as a definition of the limits of any particular embodiment. Thedrawings, together with the remainder of the specification, serve toexplain principles and operations of the described and claimed aspectsand embodiments. In the figures, each identical or nearly identicalcomponent that is illustrated in various figures is represented by alike numeral. For purposes of clarity, not every component may belabeled in every figure. In the figures:

FIG. 1A is a schematic drawing illustrating a system in accordance withone or more embodiments;

FIG. 1B is a schematic drawing illustrating a system in accordance withone or more embodiments;

FIG. 2 is a schematic drawing illustrating a system in accordance withone or more embodiments;

FIG. 3 is a graph showing the results from a first test conducted inaccordance with one or more embodiments;

FIG. 4 is a graph showing the results from a second test conducted inaccordance with one or more embodiments;

FIG. 5 is a graph showing the results from a third test conducted inaccordance with one or more embodiments;

FIG. 6 is a graph showing the results from a fourth test conducted inaccordance with one or more embodiments;

FIG. 7 is a graph showing the results from a fifth test conducted inaccordance with one or more embodiments;

FIG. 8 is a schematic drawing illustrating a processor or controllerupon which one or more embodiments may be practiced;

FIG. 9 is a schematic drawing illustrating a reactor in accordance withone or more embodiments;

FIG. 10A is a schematic drawing illustrating a reactor in accordancewith one or more embodiments;

FIG. 10B is a schematic drawing illustrating a reactor in accordancewith one or more embodiments;

FIG. 11 is a schematic drawing illustrating a system in accordance withone or more embodiments;

FIG. 12 is a schematic drawing illustrating a system in accordance withone or more embodiments; and

FIG. 13 is a schematic drawing illustrating a system in accordance withone or more embodiments.

DETAILED DESCRIPTION

Pressure to clean up contaminated sites has continued under governmentregulation which requires removal, reduction, destruction, orstabilization of environmentally hazardous chemical compounds. However,certain groundwater contaminants are difficult to treat in acost-effective manner. These contaminants gain a reputation as being“recalcitrant” primarily as a result of fundamental physicochemicalproperties that make treatment difficult.

Biodegradation (one potential method for remediating such contamination)involves using indigenous or introduced (i. e., non-indigenous) bacteriaor other microbes to degrade or digest organic chemicals transportedacross their cell membranes, thereby producing byproducts such as carbondioxide gas and water. Although biodegradation works well for certainorganic contaminants, it can be difficult or impossible to biodegraderecalcitrant organic contaminants.

1,4-dioxane is one example of a recalcitrant organic contaminant.1,4-Dioxane, otherwise referred to as simply “dioxane,” is a clearliquid that easily dissolves in water. It is used primarily as a solventin the manufacture of chemicals and as a laboratory reagent and hasvarious other uses that take advantage of its solvent properties.1,4-Dioxane is a trace contaminant of some chemicals used in cosmetics,detergents, and shampoos. However, manufacturers now reduce 1,4-dioxanefrom these chemicals to low levels before these chemicals are made intoproducts used in the home.

In accordance with one or more non-limiting embodiments, 1,4-dioxaneconcentrations in contaminated water may be less than about 1.0 mg/l.Some states may have established maximum concentration limit guidelines,such as levels of less than about 0.30 μg/l in drinking water.

The Environmental Protection Agency (EPA) identifies the most serioushazardous waste sites in the nation. These sites are then placed on theNational Priorities List (NPL) and are targeted for long-term federalclean-up activities. 1,4-Dioxane has been found in at least 31 of the1,689 current or former NPL sites. Although the total number of NPLsites evaluated for this substance is not known, the possibility existsthat the number of sites at which 1,4-dioxane is found may increase inthe future as more sites are evaluated. Since 1,4-dioxane is considereda hazardous material that contaminates ground water, there is a need fora process that will remove 1,4-dioxane from groundwater. Previously,attempts have been made to use a combination of hydrogen peroxide andultraviolet light (UV), or ozone in combination with UV light to destroy1,4-dioxane. These processes are not very efficient and may require anadditional post treatment step with peroxide to completely remove1,4-dioxane. Another process used is a regenerable charred resinmaterial that will adsorb 1,4-dioxane. However, this process results ina waste stream that contains concentrated 1,4-dioxane that requiresanother means to destroy the 1,4-dioxane such as incineration.

One or more aspects relate to a method of treating contaminatedgroundwater. According to some embodiments, the method comprisesproviding a contaminated groundwater having an initial concentration ofa recalcitrant organic contaminant to be treated, introducing apersulfate to the contaminated groundwater to produce a first treatedaqueous solution, and exposing the first treated aqueous solution toultraviolet light to produce a second treated aqueous solution, wherethe second treated aqueous solution has a concentration of therecalcitrant organic contaminant that is at least 50% less than theinitial concentration of recalcitrant organic contaminant.

According to certain aspects, the method can further comprise measuringa total organic carbon (TOC) value of the contaminated groundwater to betreated. The method may further comprise adjusting at least one of arate at which the persulfate is introduced to the contaminatedgroundwater and a dose of the ultraviolet light based on the measuredTOC value. According to a further aspect, adjusting a dose of theultraviolet light comprises at least one of adjusting an intensity ofthe UV light and adjusting an exposure time of the UV light to the firsttreated aqueous solution. According to another aspect, adjusting anexposure time of the UV light comprises adjusting a flow rate of thefirst treated aqueous solution. According to yet another aspect,adjusting an exposure time of the UV light comprises adjusting aresidence time of the first treated aqueous solution in a reactor.

According to at least one aspect, the method can further comprisemeasuring a TOC value of the second treated aqueous solution. Accordingto at least one aspect, the method further comprises recirculating atleast a portion of the second treated aqueous solution to a pointupstream from the introduction of the persulfate based on the measuredTOC value of the second treated aqueous solution. According to someaspects, the method further comprises adjusting at least one of a rateat which the persulfate is introduced to the contaminated groundwaterand a dose of the ultraviolet light based on the measured TOC value ofthe second treated aqueous solution.

In accordance with various aspects, the first treated aqueous solutionis a first treated stream and the second treated aqueous solution is asecond treated stream and the persulfate is introduced to thecontaminated groundwater upstream from the exposure of the first treatedstream to the ultraviolet light. According to one aspect, theconcentration of recalcitrant organic contaminant in the second treatedaqueous solution is at least 99% less than the initial concentration ofcontaminant.

According to at least one aspect, the method can further comprisepretreating the contaminated groundwater. According to a further aspect,pretreating the contaminated groundwater comprises introducing thecontaminated groundwater to a media filter prior to introducing thepersulfate.

In accordance with certain aspects, the contaminated groundwater isintroduced to the persulfate and exposed to the first treated aqueoussolution in a single pass.

According to at least one aspect, the second treated aqueous solution ispotable water. According to another aspect, the method may furthercomprise extracting the contaminated groundwater from a remediationsite.

One or more aspects relate to a system for treating contaminatedgroundwater. In some embodiments, the system comprises a source ofcontaminated groundwater having an initial concentration of arecalcitrant organic contaminant, a TOC concentration sensor in fluidcommunication with the contaminated groundwater, a source of persulfatefluidly connected to the source of contaminated groundwater andconfigured to introduce a persulfate to the contaminated groundwater, anactinic radiation source fluidly connected to the source of contaminatedgroundwater and configured to irradiate the contaminated groundwater,and a controller in communication with the TOC concentration sensor andconfigured to control at least one of a rate at which the persulfate isintroduced to the contaminated groundwater and a dose of irradiationapplied by the actinic radiation source based on an output signal fromthe TOC concentration sensor.

According to certain aspects, the system further comprises a reactorfluidly connected to the source of contaminated groundwater and thesource of persulfate and configured to house the actinic radiationsource. According to another aspect, the controller is configured tocontrol the dose of irradiation by controlling a residence time of thecontaminated groundwater in the reactor. According to yet anotheraspect, the controller is configured to control the dose of irradiationby controlling a flow rate of the contaminated groundwater. According toa further aspect, the actinic radiation source is positioned downstreamfrom the source of persulfate. According to at least one aspect, the TOCconcentration sensor is positioned upstream from the source ofpersulfate. According to another aspect, the TOC concentration sensor isa first TOC concentration sensor and the system further comprises asecond TOC concentration sensor in communication with the controller andpositioned downstream from the actinic radiation source. According tocertain aspects, the controller is configured to control at least one ofthe rate at which the persulfate is introduced to the contaminatedgroundwater, and a dose of irradiation applied by the actinic radiationsource based on an output signal from the second TOC concentrationsensor.

In accordance with some aspects, the system further comprises a valvefluidly connected to a treated water exiting the actinic radiationsource, and the controller is configured to control the valve based onthe output signal from the second TOC concentration sensor. According toanother aspect, the system further comprises a media filter positionedupstream from the source of persulfate.

According to at least one aspect, the system is a mobile-based platform.

In accordance with one or more aspects, ex-situ methods and systems forgroundwater remediation are disclosed.

One or more aspects can be directed to groundwater treatment systems andtechniques. The systems and techniques may utilize the use of apersulfate in combination with a source of ultraviolet (UV) light totreat groundwater contaminated with a recalcitrant organic contaminant.According to some embodiments, the groundwater is treated such that theconcentration of recalcitrant organic contaminant is reduced to levelssuch that the groundwater may be returned to the source, i. e., thelevel of recalcitrant organic contaminant falls below one or morestandards set by governing authorities. According to a further aspect,the concentration of recalcitrant organic contaminant is reduced suchthat the treated groundwater may be characterized as potable water. Forexample, according to some embodiments, the methods and systemsdisclosed herein may treat contaminated groundwater to produce potablewater. The potable water may comply with standards set bymunicipalities. As used herein the term “recalcitrant organic” when usedin reference to a contaminant refers to organic compounds that resistmicrobial degradation or are not readily biodegradable. In certaininstances, the recalcitrant organic contaminant may not degradebiologically, and remediation methods may be unable to remove enough ofthe substance to satisfy environmental regulations. Non-limitingexamples of recalcitrant organic contaminants include 1,4-dioxane,trichloroethylene (TCE), perchloroethylene (PCE), urea, isopropanol,chloroform, atrazine, tryptophan, and formic acid. Tables 1A-1D belowlist non-limiting examples of recalcitrant organic contaminants that maybe present in groundwater treated by the systems and techniquesdisclosed herein.

Tables 1A and 1B below lists various types of organic contaminants andexamples that may be treated by the systems and methods disclosedherein.

TABLE 1A Anions (not oxidized, but decomposed) Chlorate BromateHalogenated Alkanes 1,2,3-trichloropropane (1,2,3-TCP)1,1-dichloroethane 1,2-dichloroethane Trihalomethanes (Trichloromethane,Monochlorodibromomethane, etc.) Bromomethane Chloromethane HalogenatedAlkenes Tetrachloroethene Trichloroethene 1,2-cis-dichloroethene1,2-trans-dichloroethene Vinyl Chloride Alkynes AcetyleneDichloroethylene TCE Trichloroethylene PCE TetrachloroethyleneHalogentated Organic Acids Haloacetic Acids (Trichloro aceticacid,monochloroaceticacid, monochlorodibromoacetic acid, iodoacetic acids,etc.) Amines Methylamine Ethanolamine Diphenylamine Aniline PiperidineMethylethanolamine Trimethylamine Nitrosamines NDMA,N-Nitrosodimethylamine Surfactants/Algacides/Bactericides Quaternaryammonium alkyl halides Alcohols Methanol Ethanol Isopropanol ButanolPentanoI Hexanol TBA (Tert Butyl Alcohol) Acetic Acids MonochloroaceticAcid Dichloroacetic Acid Iodoacetic Acid PTFE Precursors PFOA PFOS PFNAEthers/Aldehydes 1,4-dioxane Formaldehyde Diethyl ether Polyethyleneglycol MTBE (Methyl Tertbutyl Ether) Ketones 2-pentanone (MPK) butanone(MEK) Organisms Bacteria Molds Fungi Viruses (including entero & noro)

TABLE 1B Pharmaceuticals and Personal Care Products AcetaminophenAndrostenedione Atrazine Benzo[a]pyrene Caffeine Carbamazepine DDT DEETDiazepam Diclofenac Dilantin Erythromycin Estradiol Estriol EstroneEthinylestradiol Fluorene Fluoxetine Galaxolide Gemfibrozil HydrocodoneIbuprofen lopromide Lindane Meprobamate Metolachlor Musk Ketone NaproxenOxybenzone Pentoxifylline Progesterone Sulfamethoxazole TCEPTestosterone Triclosan Trimethoprim Unreacted Monomers AcrylonitrileVinyl chloride Propylene Styrene Urethane Cyclic siloxanesHexamethylcyclotrisiloxane Decamethylcyclopentasiloxane Linear siloxanesOctamethyltrisiloxane Dodecamethylpentasiloxane Ammonia Sulfur BearingCompounds Hydrogen Sulfide Dimethyl Disulfide Dimethyl Sulfide CarbonylSulfide Polyaromatic Hydrocarbons Naphthalene Fluorene AnthraceneAromatic Hydrocarbons Benzene Cumene Xylene Phenol Benzoate BenzylamineBenzylacetate Halogenated Aromatics Benzyl chloride Benzyl bromideChlorophenol

Table 1C lists additional examples of various recalcitrant organiccontaminants and their respective class that may be treated by themethods and systems disclosed herein. One or more of these compounds maybe endocrine disruptors. Endocrine disruptors may refer to an exogenouschemical substance which inhibits or promotes various processes such asthe homeostasis of the living body, and synthesis, storage, secretion,internal transport, receptor binding, hormone activity and excretion ofvarious internal hormones involved in reproduction, development andbehavior, and is also a term which may also be named an exogenousendocrine disrupting substance, an endocrine disrupting substance, anendocrine disrupting chemical substance, an endocrine disordersubstance, or an environmental hormone.

TABLE 1C Contaminant Class Acetaminophen Pharmaceutical AndrostenedioneSteroid Atrazine Pesticide Benzo[a]pyrene PAH (polycyclic aromatichydrocarbon) Caffeine PCP (personal care product) CarbamazepinePharmaceutical DDT Pesticide DEET PCP Diazepam Pharmaceutical DiclofenacPharmaceutical Dilantin Pharmaceutical Erthromycin-H20 AntimicrobialEstadiol Steroid Estriol Steroid Estrone Steroid EthinylestradiolSteroid Fluorene PAH Fluoxetine Pharmaceutical Galaxolide FragranceGemfibrozil Pharmaceutical Hydrocodone Pharmaceutical IbuprofenPharmaceutical Iopromide Pharmaceutical Lindane Pesticide MeprobamatePharmaceutical Metolachlor Pesticide Musk Ketone Fragrance NaproxenPharmaceutical Oxybenzone PCP Pentoxifylline Pharmaceutical ProgesteroneSteroid Sulfamethoxazole Antimicrobial TCEP PCP Testosterone SteroidTriclosan Antimicrobial Trimethoprim Antimicrobial

Table 1D includes non-limiting examples of pharmaceutical and personalcare product compounds that may be treated by the systems and methodsdisclosed here. One or more of these substances may also be endocrinedisruptors.

TABLE 1D Pharmaceuticals Trimethoprim, crytomycine, lincomycin,Veterinary & human sultamethaxole, chloramphenicol, antibioticsamoxycillin Ibuprofen, diclofenac, fenoprofen, Analgesics &acetaminophen, naproxen, acetylsalicyclic anti-inflammatory drugs acid,fluoxetine, ketoprofen, indometacine, paracetamol Diazepam,carbamazepine, primidone, Psychiatric drugs salbutamol Clofibric acid,bezafibrate, fenofibric acid, Lipid regulators etofibrate, gemfibrozilMetoprolol, propranolol, timolol, sotalol, B-Blockers atenololIopromide, iopamidol, diatrizoate X-ray contrasts Estradiol, estrone,estriol, Steroids & hormones diethylstilbestrol (DES) Nitro, polycyclicand macrocyclic musks, Personal care products and phthalates FragrancesBenzophenone, methylbenzylidene Sun-screen agents camphorN,N-diethyltoluamide Insect repellants Triclosan, chloropheneAntiseptics

In accordance with at least one aspect, some embodiments involve amethod for treating contaminated groundwater. As used herein, the term“groundwater” may refer to water recoverable from subterranean sourcesas well as water recovered from surface bodies of water, such asstreams, ponds, marshes, and other similar bodies of water. Thegroundwater may be contaminated with a recalcitrant organic contaminant,as discussed above. The groundwater may have become contaminated fromany one of a number of different sources, such as industrial processes,agricultural process, such as pesticide and herbicide applications, orother processes, such as disinfection processes that produce undesirablebyproducts such as trihalomethanes.

In accordance with at least one embodiment, the methods and systemsdisclosed herein may include providing a contaminated groundwater havingan initial concentration of a recalcitrant organic contaminant.According to some embodiments, the methods and systems disclosed hereinmay include extracting or otherwise removing the contaminatedgroundwater. For instance, the contaminated groundwater may be pumpedfrom the ground or other sources using one or more pumps or otherextraction devices as part of a remediation effort. Once treated, thegroundwater may then be returned to the source or sent on for furtherprocessing. According to some embodiments, the contaminated groundwateris pumped or otherwise removed to the surface grade level where it maythen be treated according to the processes and methods discussed herein.For example, according to some embodiments, the methods and systemsdisclosed herein may include extracting the contaminated groundwaterfrom a remediation site. In at least one embodiment, one or moreextraction wells and extraction equipment, such as pumps, may be usedfor pumping contaminated groundwater to the surface to be treated. Oncetreated, a pump or other distribution system may be used to return thetreated groundwater to the source or otherwise re-introduce the treatedgroundwater back into the environment. In certain instances thecontaminated groundwater may be stored in a holding tank or vessel priorto treatment, and in some cases treated water produced by the processesdisclosed herein may be added or otherwise mixed with the contaminatedgroundwater.

In accordance with one or more aspects, the contaminated groundwater mayhave a level of total dissolved solids (TDS) that is in a range of about100 mg/L to about 5000 mg/L, and in some instances may be in a range ofabout 200 mg/L to about 2000 mg/L, although these values can varydepending on the geographic location and other factors. As a source ofcomparison, water with a TDS level of 1000-1500 mg/L is considereddrinkable, with some standards having a 500 mg/L TDS limit for domesticwater supplies.

In accordance with another aspect, the methods and systems disclosedherein may be connected or otherwise in fluid communication with asource of contaminated groundwater. For instance, the contaminatedgroundwater may be pumped or otherwise delivered to the disclosed systemfor treatment.

According to various aspects, the concentration of recalcitrant organiccontaminant in the groundwater is high enough to exceed limitsestablished by government agencies. According to some embodiments, thesystems and methods disclosed herein treat the groundwater such that theconcentration level of the recalcitrant organic contaminant is reduced.In some instances, the systems and methods disclosed herein reduce theconcentration of the recalcitrant organic contaminant to a level thatcomplies with government standards or guidelines. According to oneembodiment, the concentration of recalcitrant organic contaminant isreduced to a level such that the treated groundwater may be returned tothe source. For example, the EPA's standard for the concentration of1,4-dixoane in drinking water is 1 μg/L (1 ppb). The methods and systemsdisclosed herein may be scaled to treat substantially all concentrationsof recalcitrant organic contaminant that may be present in thegroundwater. For instance, according to some embodiments, the initialconcentration of recalcitrant organic contaminant, such as dioxane, inthe groundwater may be in a range from about 5 ppb to about 800 ppb.

In accordance with at least one aspect, a persulfate may be introducedto the contaminated groundwater. As used herein, the term “persulfate”is used in reference to a composition that when combined with an aqueoussolution contributes at least one of the peroxomonosulfate (orperoxymonosulfate) ion SO₅ ⁻² and the peroxodisulfate (orperoxydisulfate) ion S₂O₈ ⁻². Non-limiting examples of persulfatesinclude alkali and alkali metal persulfates such as sodium persulfate,potassium persulfate, and any other Group I metal persulfate, andammonium persulfate or ammonium persulfate, peroxydisulfate salts suchas alkali and alkali metal peroxydisulfate and ammonium peroxydisulfate,acids such as peroxydisulfuric acid, peroxymonosulfuric acid or Caro'sacid, as well as combinations thereof. According to certain aspects, thepersulfate may be stored in a tank or other vessel and introduced to thecontaminated groundwater through a controllable valve or othercontrollable conduit such that the rate of persulfate introduced to thecontaminated groundwater may be controlled.

In accordance with another aspect, the contaminated groundwater may beexposed to a source of ultraviolet (UV) light. For instance, the systemsand methods disclosed herein may include the use of one or more UVlamps, each emitting light at a desired wavelength in the UV range ofthe electromagnetic spectrum. For instance, according to someembodiments, the UV lamp may have a wavelength ranging from about 180 toabout 280 nm, and in some embodiments, may have a wavelength rangingfrom about 185 nm to about 254 nm.

According to some embodiments, a source of persulfate may first beintroduced to the contaminated groundwater, which may be followed byexposure of the contaminated groundwater to UV light. According to otherembodiments, the persulfate addition and the UV exposure may occur atapproximately the same time, i. e., simultaneously or nearlysimultaneously. According to various aspects, the persulfate and the UVlight function to oxidize the recalcitrant organic contaminant intonon-hazardous compounds, including carbon dioxide and water. Forexample, persulfate and UV may react with recalcitrant organiccontaminants as shown below by Equation 1:

In accordance with certain aspects, the chemical reaction of persulfatewith UV may be expressed as shown below by Equation 2:

Further, the free sulfate radicals formed when the persulfate isactivated by UV react with the organic contaminants by removingelectrons from the organic molecule to produce organic radials, as shownbelow in Equation 2A for the carboxylate ion:CH₃CO₂ ⁻+SO₂ ^(•−)→CH₃CO₂ ^(•)+SO₄ ²⁻|→^(•)CH₃+CO₂+SO₄ ²⁻  Equation 2A:The sulfate radical reacts with aromatic or heterocyclic contaminantsvia an electron transfer mechanism to produce a radical cation, as shownbelow by Equation 2B:

Without being bound by theory, it is believed that the free sulfateradicals are responsible for the oxidation of TOC, either directly, orby reacting with other radicals and oxidants.

According to various aspects, the combination of persulfate with UVlight is more effective than using either component on its own. Forinstance, in the examples discussed below, the combination of persulfatewith UV light was shown to decrease the total organic carbon (TOC)concentration by nearly 100% for many contaminants, whereas UV lightalone reduced the TOC concentration to a lesser degree. For example, theTOC concentration for urea was only reduced 9% by UV light alone, butwas reduced by 100% when persulfate was used in combination with UVlight. Similarly, the initial TOC concentration for 1,4-dioxiane wasreduced by nearly 100% when persulfate was used in combination with UV,whereas UV alone only reduced this amount by about 72%.

According to various embodiments, the treatment of the contaminatedgroundwater with the persulfate and the UV light may reduce the initialconcentration of recalcitrant organic contaminant in the groundwater byat least 50%. In some embodiments, the treatment with persulfate and UVlight may reduce the initial concentration of recalcitrant organiccontaminant by at least 70%, in some embodiments by at least 90%, by atleast 99%, and in some embodiments, the treatment may result in 100%removal, or to levels that are not detectable. According to at least oneembodiment, substantially all of the recalcitrant organic contaminantmay be removed from the contaminated groundwater, meaning that 99-100%is removed.

In accordance with at least one aspect, one or more embodiments mayinvolve a method of treating water. The method can comprise providing acontaminated groundwater having an initial concentration of recalcitrantorganic contaminant to be treated. The method also comprises introducinga persulfate to the contaminated groundwater to produce a first treatedaqueous solution. The method also comprises exposing the first treatedaqueous solution to ultraviolet light to produce a second treatedaqueous solution. In some embodiments, the second treated aqueoussolution has a concentration of recalcitrant organic contaminant that isat least 50% less than the initial concentration of recalcitrant organiccontaminant. The method may also comprise measuring a total organiccarbon (TOC) value of the contaminated groundwater to be treated, andadjusting at least one of a rate at which the persulfate is introducedto the contaminated groundwater and a dose of the ultraviolet lightbased on the measured TOC value. In some embodiments, adjusting the rateat which the persulfate is introduced to the contaminated groundwatermay include adjusting a flow rate of persulfate. According to otherembodiments, adjusting the rate at which the persulfate is introducedmay include adjusting the concentration of the persulfate. For instance,the concentration of persulfate may be increased or decreased, dependingon one or more measured TOC readings. According to at least oneembodiment, a TOC value of the second treated aqueous solution may bemeasured. A portion of the second treated aqueous solution may berecirculated to a point upstream from the introduction of persulfatebased on the measured TOC value of the second treated aqueous solution.In some instances, a portion of the second treated aqueous solution maybe recirculated based on the measurement of one or both the TOC value ofthe contaminated groundwater and the TOC value of the second treatedaqueous solution. For instance, in some embodiments, the treatment bythe persulfate and the UV may reduce the concentration of therecalcitrant organic contaminant to a desired or otherwise predeterminedlevel in a single pass. According to at least one aspect, the secondtreated aqueous solution is potable water. According to otherembodiments, at least a portion of the contaminated groundwater may beexposed to the persulfate and the UV in multiple passes for purposes ofreducing the concentration of the recalcitrant organic contaminant to anacceptable level. The second treated aqueous solution may berecirculated for other reasons as well, such as to dilute theconcentration of contaminants in the groundwater in instances where thegroundwater is stored or otherwise held in a container or vessel priorto treatment.

According to some embodiments, adjusting a dose of the ultraviolet lightmay comprise at least one of adjusting an intensity of the UV light andadjusting an exposure time of the UV light to the first treated aqueoussolution. For instance, the first treated aqueous solution may be heldor otherwise contained within a reactor or vessel and be exposed to UVlight for a predetermined exposure time while the solution is housedwithin the reactor or vessel. According to some embodiments, baffles orother flow control devices positioned within the reactor or vessel mayalso contribute to containing the first treated aqueous solution for apredetermined exposure time. According to other embodiments, adjusting adose of the ultraviolet light may comprise adjusting a flow rate of thefirst treated aqueous solution. For instance, the first treated aqueoussolution may pass through a conduit that is configured to allow UV lightto pass through to the conduit to irradiate the first treated aqueoussolution. According to other embodiments, the dose of the UV light maybe adjusted by adjusting a power setting of the UV light, or byadjusting the wavelength of the UV lamp.

According to some embodiments, at least one of the intensity of the UVlight and the dose of UV light may be adjusted based on one or moreoperating parameters, such as a TOC value. UV dose, when applied to apersulfate, is a measure of the total lamp electrical energy applied toa fixed volume of water. The units are usually measured in kWh/1000gallons. This parameter combines flowrate, residence time, and lightintensity into a single term. The dose may vary from one type ofcontaminated water to the other. However, the dosage may be set todestroy virtually all types of contaminants to any level required. Thecalculation for either batch or flowthrough treatment is shown below byEquations 3 and 4, respectively:

Batch:UV Dose=(lamp power (kW)×time (hrs)×1000)/(batch volume (gal.)  Equation3:Flowthrough:UV Dose=(lamp power (kW)×1000/(flow (gpm)×60)  Equation 4:

According to at least one embodiment, a controller, as discussed furtherbelow, may be used to control the UV dose for batch and flowthroughprocesses, including the lamp power, the exposure time, the and the flowrate.

According to at least one embodiment, the contaminated groundwater maybe pretreated. For instance, the contaminated groundwater may bepretreated prior to the introduction of persulfate. Pretreatment mayfunction to remove any one or more undesirable components from thecontaminated groundwater, such as substances that may interfere with theprocesses and systems disclosed herein. For example, pretreatment mayinvolve a water disinfectant process, a sediment removal process, or theremoval of any other undesired component, such as a water deionizationprocess. In accordance with at least one embodiment, pretreatment may beperformed using a media filter, as described further below. According toother embodiments, pretreatment may be performed by adding or otherwiseexposing the contaminated groundwater to one or more pretreatmentsubstances. For instance, chlorine may be added as a disinfectant to thecontaminated groundwater.

In accordance with at least one embodiment, the methods and systemsdisclosed herein include a media filter. The media filter may functionto remove any one or more undesirable components from the contaminatedgroundwater, such as dissolved solids or particulates which mayinterfere with the function of the UV light or clog components of thefiltration system.

The media filter may be any one of a number of different types of mediafilters, including a particulate filter, such as a screen filter, sandfilter, a bag filter, or a filter cartridge, and may contain one or moretypes of media, such as, activated carbon or other carbons, nut shells,sand, resins, and other types of adsorbents. For example, the mediafilter may function to remove particulates or otherwise reduce theturbidity of the contaminated groundwater.

A level of total dissolved solids (TDS) in the contaminated groundwatermay be reduced. According to some embodiments, ion exchange resin may beused. Ion exchange softening may be implemented as a hardness removalpretreatment process. The ion exchange resin may function to reduce thehardness of the contaminated groundwater. For example, in certaininstances a mixed bed deionizer may be used in the systems and methodsdisclosed herein. A mixed bed deionizer uses both cation and anionregenerative ion exchange resin beads, which are mixed together toremove impurities. The mixed bed deionizer allows water to make repeatedcontact with the cation and anion beads, and remove or reduce theconcentration of undesirable ions in the contaminated groundwaterthrough the process of ion exchange.

Other non-limiting examples of pretreatment devices include reverseosmosis devices, electrodialysis devices, electrodeionization devices,and distillation devices. The pretreatment device may also be placed atone or more locations in the process where a device with a particularfunctionality may be desired. For instance, an additional media filtermay be positioned in the recirculating loop of the second treatedaqueous solution.

Methods disclosed herein may incorporate the removal of iron from one ormore process streams. Conventionally, iron is used as an activatingoxidant in groundwater treatment. However, the presence of iron in thecontaminated groundwater may have an adverse effect with persulfate.Iron compounds typically react with persulfate to prematurely activateand then deactivate the persulfate. The efficacy of the persulfatetreatment may be reduced when the persulfate is deactivated before beingintroduced into the contaminated groundwater and before irradiation withultraviolet light. To mitigate the reduced efficacy, iron may be removedupstream from dosing the groundwater with persulfate. In certainembodiments, iron may be removed from a water stream used to make up thepersulfate solution.

In accordance with one or more embodiments, pretreatment for ironremoval may prevent decline in UV lamp intensity readings as ironfouling of the quartz sleeves may be prevented. In turn, dioxane removalmay be enhanced. Conventionally, frequent chemical cleaning may berequired. In at least some embodiments, an effective iron removalprocess upstream may extend the time in service between chemicalcleaning by one or two orders of magnitude.

A pretreatment operation may be performed to remove iron from thecontaminated groundwater stream. The pretreatment may produce apretreated groundwater having a concentration of iron less than aconcentration sufficient to deactivate the persulfate. The pretreatmentoperation may be designed to correspond with a concentration ofpersulfate introduced into the contaminated groundwater. For instance,in some embodiments, the groundwater may be pretreated to have aconcentration of iron less than a concentration sufficient to deactivate50% of the persulfate. The groundwater may be pretreated to have aconcentration of iron less than a concentration sufficient to deactivate30%, 20%, 10%, 5%, or 1% of the persulfate. In some non-limitingembodiments, groundwater may contain less than about 10 mg/l of iron.Even low concentrations of iron, for example, about 0.5 mg/l or less,can be associated with adverse conditions including water discoloration.

The pretreatment may produce a pretreated groundwater havingsubstantially no iron. In some embodiments, the pretreatment may producea pretreated groundwater having a concentration of iron of 0.5 mg/L orless. For instance, the pretreated groundwater may have a concentrationof iron of 0.4 mg/L or less, 0.3 mg/L or less, 0.2 m/L or less, 0.1 mg/Lor less, or 0.05 mg/L or less.

Iron in the contaminated groundwater may be removed by treatment with afiltration media. The filtration media may be selected for removal ofiron. For instance, the filtration media may comprise at least one ofmanganese dioxide, manganese oxide, and silica. The filtration media maybe a catalytic filtration media. In an exemplary embodiment, thefiltration media may comprise manganese oxide. Such a filtration mediamay remove iron by oxidizing iron upon contact and capturing theoxidized iron. Commercially available filtration media include, forexample, manganese greens and (distributed by Nelson Co., Norton, Ohio),birm (distributed by Clack Corporation, Windsor, Wis.), and DMI-65(distributed by Quantum Filtration Medium, Collie, Wash., Australia).The pretreatment may further comprise adjusting a pH of the contaminatedgroundwater to be compatible with iron removal by the selectedfiltration media.

Iron in the contaminated groundwater may be removed by oxidation. Anoxidizing agent may be introduced into the contaminated groundwater toprecipitate the iron. The precipitated iron may then be removed by afiltration operation, for example, a gravity filtration or pressurizedfiltration. The oxidant may be selected from chlorine, permanganate,oxygen, ozone, and peroxide. In some embodiments, the contaminatedgroundwater may be dosed with chlorine. The chlorine may be introducedat a rate of between about 1 and 2 parts chlorine per one part iron. Thecontaminated groundwater may be dosed with oxygen. The oxygen may beintroduced at a rate of between about 0.1 and 0.2 parts dissolved oxygenper one part iron. In some embodiments, the oxygen may be introduced byaerated. Aeration may be achieved, for example, with an aeration pump.The pretreatment may further comprise adjusting a pH of the contaminatedgroundwater to be compatible with iron oxidation by the selectedoxidant.

In some embodiments, iron may be removed from a stream of water used tomake up the persulfate solution. The iron may be removed by any of themethods previously described herein. Additionally, the persulfatesolution may be made up with high purity water. For example, thepersulfate solution may be made up with deionized water or reverseosmosis permeate. Thus, methods may comprise treating a stream with ionexchange or reverse osmosis to produce the persulfate solution makeupwater. The water used to makeup the persulfate solution may besubstantially free of iron. In some embodiments, the water used to makeup the persulfate solution may have less than 0.2 mg/L of iron. Thewater used to makeup the persulfate solution may have an ironconcentration of less than 0.1 mg/L, less than 0.05 mg/L, less than0.025 mg/L, or less than 0.01 mg/L.

Additionally, removal of iron upstream from the source of ultravioletlight may reduce a rate of fouling of the UV quartz sleeve(s).Typically, quartz sleeves are subject to a periodic cleaning operationwhich may include wiping the quartz sleeve to remove foulants, includingiron. An example of a conventional cleaning agent may be citric acid.The systems and methods disclosed herein may facilitate maintenance ofthe treatment system, for example, by reducing the number of requiredmaintenance operations or allowing the treatment system to operate for alonger period of time between quartz sleeve cleaning processes.

Methods disclosed herein may comprise cleaning the UV quartz sleeves.Iron may be removed to prevent build-up on the sleeves that house UVlamps. Such build-up may decrease the amount of UV light available toactivate the persulfate, thus decreasing the removal of contaminants. Insome embodiments, a wiper may be used to clean the quartz sleeves.Wipers may address organics, metals and particulates. A wiping operationmay be manual or automatic. In some embodiments involving automaticwiping, system operation may run substantially continuously.Pretreatment to remove iron as disclosed herein may improve theoperating time as the sleeves should not be fouled. Chemical cleaningmay therefore not be required. Periodic chemical cleaning, such as withcitric acid, may be implemented but at a reduced frequency compared toconventional operation or may not be necessary at all. Wipers may addexpense but may be used in conjunction with pretreatment as disclosedherein to address iron. In some embodiments, pretreatment alone and nowipers and/or chemical cleaning may be implemented.

In some embodiments, pretreatment of the contaminated groundwater mayincrease operating time of the system between quartz sleeve maintenanceoperations by at least about 50%. In some embodiments, pretreatment ofthe contaminated groundwater may increase operating time of the systembetween quartz sleeve maintenance operations by at least about 100%, forexample, by at least about 150%, by at least about 200%, by at leastabout 300%, or by at least about 400%. Methods disclosed herein maycomprise measuring a concentration of iron in the contaminatedgroundwater. The method may comprise adjusting a rate at which thepersulfate is introduced based on the measured concentration of iron.For example, the persulfate may be introduced at a rate at which at mostabout 30%, 20%, 10%, 5%, or 1% of the persulfate will be deactivated bythe concentration of iron in the contaminated groundwater. The methodmay comprise adjusting the pretreatment of the contaminated groundwater.For example, the method may comprise adjusting a rate at which theoxidant is introduced into the contaminated groundwater, as previouslydescribed herein. The method may additionally or alternatively compriseadjusting a rate at which the contaminated water is filtered by themedia filter, as previously described herein. The filtration rate may beadjusted, for example, by varying flowrate of the contaminatedgroundwater through the filtration media.

The methods disclosed herein may produce treated water having aconcentration of a recalcitrant organic contaminant that is less thanthe contaminated groundwater. In some embodiments, the concentration ofrecalcitrant organic contaminant in the treated water may be 10 ppb orless. The concentration of recalcitrant organic contaminant in thetreated water may be 5 ppb or less, 4 ppb or less, 3 ppb or less, 2 ppbor less, 1 ppb or less, or 0.5 ppb or less. One or more recalcitrantorganic contaminants may exist together in the contaminated groundwater.

In accordance with at least one aspect, some embodiments thereof caninvolve a system for treating contaminated groundwater. The system maycomprise a source of contaminated groundwater having an initialconcentration of recalcitrant organic contaminant and a TOCconcentration sensor in fluid communication with the contaminatedgroundwater. The system may also include a source of persulfate fluidlyconnected to the source of contaminated groundwater. The source ofpersulfate may be configured to introduce a persulfate to thecontaminated groundwater. The system may also comprise an actinicradiation source that is fluidly connected to the source of contaminatedgroundwater. The actinic radiation source may be configured to irradiatethe contaminated groundwater. The system may also include a controllerthat is in communication with the TOC concentration sensor and isconfigured to control at least one of a rate at which the persulfate isintroduced to the contaminated groundwater and a dose of irradiationapplied by the actinic radiation source based on an output signal fromthe TOC concentration sensor.

FIG. 1A schematically embodies a system 100A in accordance with one ormore aspects. System 100A can be representative of a water treatmentsystem that removes recalcitrant organic contaminants from contaminatedgroundwater. According to some embodiments, system 100A may be a watertreatment system that reduces a concentration, content, or level of oneor more impurities or contaminants that may be present in contaminatedgroundwater. In at least one embodiment, groundwater that has beentreated by system 100A may be reintroduced to the environment. Accordingto other embodiments, groundwater that has been treated by system 100Amay be further processed in downstream processing operations. Accordingto various aspects, system 100A is representative of a system thatincludes a sequential treatment method, whereby persulfate is introducedto the contaminated groundwater prior to exposure to UV light, and mayinclude a series of conduits where the contaminated groundwater istransported from one treatment operation to the next. In contrast, FIG.1B exemplifies a system 100B whereby a reactor 145 is used combine oneor more treatment operations, such as the persulfate and UV, and isdiscussed further below.

As exemplarily illustrated, system 100A may comprise a source ofcontaminated groundwater 102 that has an initial concentration ofrecalcitrant organic contaminant, a media filter 110, a source ofpersulfate 115, a source of UV light 125, one or more sensors 130 a and130 b, which in some embodiments may be TOC concentration sensors, and acontroller 150.

According to some embodiments, the contaminated groundwater 102 may bepretreated by passing it through the media filter 110 to remove any oneor more undesired species, such as particulates or ionic species. Themedia filter 110 may be provided and characterized as previouslydiscussed. Although not shown, other pretreatment devices may also beused to pretreat the contaminated groundwater 102, besides the mediafilter 110, such as pretreatment devices that disinfect the contaminatedgroundwater 102. According to some embodiments, the treatment system maynot include a media filter and may include some other type ofpretreatment device, and in certain instances, no pretreatment device isused to pretreat the contaminated groundwater.

A source of persulfate 115 may be introduced to the contaminatedgroundwater 102 to produce a first treated aqueous stream 104. Thesource of persulfate 115, may be any one or more persulfate species asdescribed above, and may be introduced to the source of groundwater in anumber of different ways. For example, the source of persulfate may bedispensed through a valve through a conduit that is connected to aconduit containing the contaminated groundwater. As discussed furtherbelow, the source of persulfate 115 may be controlled by the controller150. According to some embodiments, the introduction of persulfate 115may be adjusted and controlled based on characteristics or measured orcalculated parameters of the system, such as measured parameters of theinlet contaminated groundwater or treated water, such as water that hasbeen treated by the persulfate and UV. Non-limiting examples of thesemeasured parameters include TOC concentration, temperature, and flowrate. For instance, the rate at which the persulfate 115 is introducedto the contaminated groundwater or the concentration level of thepersulfate 115 that is introduced to the contaminated groundwater may becontrolled by the controller 150 based on a measured TOC value of watertaken by sensor 130 a. The control of the rate at which persulfate 115is introduced may be accomplished through the use of one or more flowcontrol devices, such as a valve or pump. The source of persulfate maybe stored locally in a tank or vessel and pumped through one or morepumps, valves, and conduits to be introduced to the contaminatedgroundwater. The persulfate 115 may be introduced at a certainconcentration level to the contaminated groundwater. For instance,according to some embodiments, the persulfate 115 may be added at aconcentration level in a range from about 1 ppb to about 1000 ppb perppb TOC (i. e., the initial concentration that may be measured by sensor130 a), and in some embodiments, the persulfate may be added at aconcentration level in a range from about 1 ppb to about 500 ppb per ppbTOC. In other embodiments persulfate may be added at a concentrationlevel in a range from about 1 ppb to about 200 ppb. As will beunderstood, the concentration level of persulfate may be dependent on anumber of different factors, including the type of application, the typeof contaminant, and/or the concentration of contaminant in thegroundwater. For instance, the concentration level of persulfate may bea function of various design parameters, including residence time,reactor dimensions, UV lamp characteristics, TOC composition andconcentration, as well as other factors including capital and operatingcosts, as well as the available footprint.

The first treated aqueous stream 104 treated by the persulfate 115 maybe exposed to a source of ultraviolet light 125 to produce a secondtreated aqueous solution 106. According to some embodiments, the sourceof ultraviolet light 125 may be characterized as an actinic radiationsource, otherwise referred to herein as an actinic radiation reactor.The actinic radiation reactor can comprise a vessel that includes one ormore arrays of tubes. According to some embodiments, the actinicradiation reactor may comprise a first array of tubes in the vessel. Thefirst array of tubes can comprise a first set of parallel tubes, and asecond set of parallel tubes. Each tube can comprise at least oneultraviolet lamp and each of the parallel tubes of the first set ispositioned to have its longitudinal axis orthogonal relative to thelongitudinal axis of the tubes of the second set. According to someembodiments, one or more tubes are arranged in parallel to thelongitudinal axis of the reactor. For instance, the first treatedaqueous stream 104 may pass through an actinic radiation reactor thatcomprises one or more parallel tubes that are positioned parallel to thelongitudinal axis of the reactor. The first treated aqueous stream 104may enter one end of the reactor and flow along the longitudinal axis tothe other end of the reactor, and thereby be exposed to UV light, i. e.,a path oriented configuration. According to other embodiments, a crossflow configuration is used. As discussed further below, ultravioletlamps may be positioned within quartz sleeves or tubes that protect thelamp from fluids. In addition, the reactor may be constructed fromcorrosion-resistant material such as stainless steel.

Commercially available sources of actinic radiation systems includethose from, for example, Quantrol, Naperville, Ill., as the AQUAFINE® UVsystem, and from Aquionics Incorporated, Erlanger, Ky.

In certain embodiments, the ultraviolet lamps can be operated at one ormore illumination intensity levels. For example, one or more lamps canbe used that can be adjusted to operate at a plurality of illuminationmodes, such as at any of dim, rated, and boost mode, for example, a low,medium, or high mode. The illumination intensity of one or more lampscan be adjusted and controlled based on characteristics or measured orcalculated parameters of the system, such as measured parameters of theinlet contaminated groundwater or treated water, such as water that hasbeen treated by the persulfate and UV. Non-limiting examples of thesemeasured parameters include TOC concentration, temperature, and flowrate. The illumination intensity of one or more lamps can also beadjusted and controlled based on the concentration or amount ofpersulfate added to the system. For example, the one or more lamps canbe used in a dim mode up to a predetermined threshold value of ameasured parameter of the system, such as a first TOC concentration. Theone or more lamps can be adjusted to rated mode if the measured orcalculated TOC concentration reaches or is above a second TOCconcentration, which may be above the threshold value. The one or morelamps can further be adjusted to a boost mode if the measured orcalculated TOC concentration reaches or is above a second thresholdvalue.

The controller 150 may be in communication with one or more sensors orinput devices that are configured to provide an indication orrepresentation of at least one property, characteristic, state orcondition of at least one of a process stream, a component, or asubsystem of treatment system 100A. For example, controller 150 may beoperatively coupled or otherwise configured to receive input signalsfrom any one or more sensors 130 a and 130 b. The controller 150 mayalso be operatively coupled to receive input signals from thecontaminated groundwater 102 or any other water stream in the system.The input signals can also be representative of any property of thewater, and may provide an indication of the resistivity or conductivity,the flow rate, the TOC value, the temperature, the pressure,concentration values of a particular compound or species, the amount ofbacteria, the dissolved oxygen content, and/or the dissolved nitrogencontent. Although only sensors 130 a and 130 b are particularlydepicted, additional sensors may be utilized, for example, one or moretemperature, conductivity, or resistivity sensors in system 100A. Forinstance, an additional sensor may be positioned to measure one or moreproperties of the first treated aqueous stream 104, such as thepersulfate concentration.

Controller 150 can be configured to receive any one or more inputsignals and generate one or more drive, output, and control signals toany one or more components of the system 100A. As illustrated, thecontroller 150 may, for example, receive an indication of a flow rate, aTOC level, or both, of the contaminated groundwater 102, the secondtreated aqueous solution 106, or from another position within thesystem. The controller 150 may generate and transmit a drive signal orotherwise control any of the media filter 110, source of persulfate 115,source of UV light 125, and the second treated aqueous stream 106 inresponse to the input signals. For instance, the controller 150 maygenerate and transmit a drive signal to the source of persulfate 115 to,if necessary, adjust the rate of addition of persulfate introduced intothe contaminated groundwater 102. The drive signal may be based on oneor more input signals and a target or predetermined value or set-point.For instance, if the input signal that provides a representation of theTOC value of the contaminated groundwater 102 or second treated aqueousstream 106 is above a target TOC value or a range of acceptable TOCvalues, i. e., a tolerance range, then the drive signal can be generatedto increase an amount or a rate of addition of the persulfate 115 and/ora dose of UV light from UV source 125. The target value may beapplication specific and may vary from installation to installation andbe dependent on standards established by local or federal governments ordownstream processing or use requirements.

In some embodiments, the controller 150 may, for example, receive anindication of a flow rate and/or a TOC concentration or level andgenerate and transmit a drive signal to the source of persulfate 115and/or the source of UV 125, such as the lamps of the UV source 125 toadjust or modify at least one of the one or more lamps in operation andthe intensity of the lamps. The drive signal can be based on the one ormore input signals and a target or predetermined value or set-point, orthreshold value. For example, if the input signal that provides arepresentation of the TOC value of the contaminated groundwater 102 orsecond treated aqueous stream 106 is above the target TOC value orthreshold value, or a range of acceptable TOC values, i. e., a tolerancerange, then the drive signal can be generated to adjust the rate ofpersulfate 115 introduced to the contaminated groundwater 102 and/ordose administered by the UV source 125, such as by adjusting at leastone of the lamp configuration and the lamp intensity. In someembodiments, the controller 150 may also receive an indication of apersulfate amount or rate of addition, and generate and transmit a drivesignal to the source of persulfate 115 and/or the UV source 125 inresponse to the input signal associated with the persulfate amount, suchas the persulfate concentration in one or more of the water streams ofthe system. According to some embodiments, the controller 150 maygenerate and transmit control signals to, for example, energize oradjust an intensity or power of output radiation emitted by UV source125. Thus, depending on the amount or rate of addition of persulfate 115and/or the level of TOC in the contaminated groundwater 102, the controlsignal may be increased or decreased appropriately, incrementally, orproportionally.

The controller 150 may be configured in a feedback arrangement andgenerate and transmit one or more control signals to any one of thesource of persulfate 115 and the UV source 125. For instance, the TOCvalue or the resistivity, or both, of the second treated aqueoussolution 106 may be utilized to generate control signals to any ofcontaminated groundwater 102, the source of persulfate 115, and the UVsource 125.

During periods of high initial TOC fluctuations, a feedforward controlmay be utilized to compensate for instrument delay. This technique mayallow the addition of persulfate 115 at a surplus value relative to theamount of contaminants. During periods of stable TOC levels, thefeedback approach may be utilized with or without the feedforwardcontrol.

Controller 150 may be implemented using one or more processors asschematically represented in FIG. 8. Controller 150 may be, for example,a general-purpose computer such as those based on an Intel PENTIUM®-typeprocessor, a Motorola PowerPC® processor, a Sun UltraSPARC® processor, aHewlett-Packard PA-RISC® processor, or any other type of processor orcombinations thereof. Alternatively, the control system may includespecially-programmed, special-purpose hardware, for example, anapplication-specific integrated circuit (ASIC) or controllers intendedfor analytical systems.

Controller 150 may include one or more processors 805 typicallyconnected to one or more memory devices 850, which can comprise, forexample, any one or more of a disk drive memory, a flash memory device,a RAM memory device, or other device for storing data. Memory device 850is typically used for storing programs and data during operation of thesystems 100A and 100B and/or controller 150. For example, memory device850 may be used for storing historical data relating to the parametersover a period of time, as well as operating data. Software, includingprogramming code that implements embodiments, can be stored on acomputer readable and/or writeable nonvolatile recording medium, andthen typically copied into memory device 850 wherein it can then beexecuted by processor 805. Such programming code may be written in anyof a plurality of programming languages, for example, Java, VisualBasic, C, C #, or C++, Fortran, Pascal, Eiffel, Basic, COBAL, or any ofa variety of combinations thereof.

Components of controller 150 may be coupled by an interconnectionmechanism 810, which may include one or more busses, e. g., betweencomponents that are integrated within a same device, and/or a network,e. g., between components that reside on separate discrete devices. Theinterconnection mechanism typically enables communications, e. g., data,instructions, to be exchanged between components of the system.

Controller 150 may also include one or more input devices 820 receivingone or more input signals i₁, i₂, i₃, . . . , i_(n), from, for example,a keyboard, mouse, trackball, microphone, touch screen, and one or moreoutput devices 830, generating and transmitting, one or more output,drive or control signals, s₁, s₂, s₃, . . . , s_(n), to for example, aprinting device, display screen, or speaker. In addition, controller 150may contain one or more interfaces 860 that can connect controller 150to a communication network (not shown) in addition or as an alternativeto the network that may be formed by one or more of the components ofthe system.

According to one or more embodiments, the one or more input devices 820may include components, such as but not limited to, valves, pumps, andsensors 130 a and 130 b that typically provide a measure, indication, orrepresentation of one or more conditions, parameters, or characteristicsof one or more components or process streams of systems 100A and 100B.Alternatively, the sensors, the metering valves and/or pumps, or all ofthese components may be connected to a communication network that isoperatively coupled to the controller 150. For example, sensors 130 aand 130 b may be configured as input devices that are directly connectedto the controller 150, metering valves and/or pumps of associated withthe source of persulfate 115 or positioned anywhere else in the systemmay be configured as output devices that are connected to the controller150, and any one or more of the above may be coupled to a computersystem or an automated system, so as to communicate with the controller150 over a communication network. Such a configuration permits onesensor to be located at a significant distance from another sensor orallow any sensor to be located at a significant distance from anysubsystem and/or the controller, while still providing datatherebetween.

The controller 150 may comprise one or more storage media such as acomputer-readable and/or writeable nonvolatile recording medium in whichsignals can be stored that define a program or portions thereof to beexecuted by, for example, one or more processors 805. The one or morestorage media may, for example, be or comprise a disk drive or flashmemory. In typical operation, processor 805 can cause data, such as codethat implements one or more embodiments, to be read from the one or morestorage media into, for example, memory device 840 that allows forfaster access to the information by the one or more processors than doesthe one or more media. Memory device 840 is typically a volatile, randomaccess memory such as a dynamic random access memory (DRAM) or staticmemory (SRAM) or other suitable devices that facilitates informationtransfer to and from processor 805.

Although the controller 150 is shown by way of example as one type ofcomputer system upon which various aspects may be practiced, it shouldbe appreciated that the embodiments are not limited to being implementedin software, or on the computer system as exemplarily shown. Indeed,rather than being implemented on, for example, a general purposecomputer system, the control system, or components or subsystemsthereof, may be implemented as a dedicated system or as a dedicatedprogrammable logic controller (PLC) or in a distributed control system.Further, it should be appreciated that one or more features or aspectsmay be implemented in software, hardware or firmware, or any combinationthereof. For example, one or more segments of an algorithm executable byprocessor 805 can be performed in separate computers, each of which canbe in communication through one or more networks.

Although not explicitly shown, system 100A may also include an in-linemixer that functions to mix the contaminated groundwater 102 with thesource of persulfate 115 prior to being exposed to the source of UVlight 125. This may ensure even distribution of the persulfate speciesthroughout the contaminated groundwater 102 and allow for a moreefficient process when UV light is applied.

FIG. 1B schematically embodies a system 100B in accordance with one ormore aspects. Like System 100A, System 100B can be representative of awater treatment system that removes recalcitrant organic contaminantsfrom contaminated groundwater. As such, system 100B may be a watertreatment system that reduces a concentration, content, or level of oneor more impurities or contaminants that may be present in contaminatedgroundwater, and according to at least one embodiment, groundwater thathas been treated by system 100B may be reintroduced to the environment.According to other embodiments, groundwater that has been treated bysystem 100B may be further processed in downstream processingoperations. According to various aspects, system 100B is representativeof a system that includes a batch treatment method, whereby persulfate115 is introduced to a reactor 145 that contains the contaminatedgroundwater 102 and the reactor 145 houses or otherwise includes asource of UV light. The reactor 145 allows for the option of sequentialtreatment, i. e., the introduction of persulfate 115 followed by UVexposure, a simultaneous treatment, i. e., persulfate and UV lightexposure are done at the same time, is also possible using the reactor145.

As exemplarily illustrated, system 100B is similar to system 100B andmay comprise a source of contaminated groundwater 102 that has aninitial concentration of recalcitrant organic contaminant, a mediafilter 110, a source of persulfate 115, one or more sensors 130 a and130 b, which in some embodiments may be TOC concentration sensors, and acontroller 150, as previously described and discussed. However, system100B includes the reactor 145 where one or more treatment operations mayoccur. According to some embodiments, the reactor 145 may be configuredas an irradiation reactor that is fluidly connected to the contaminatedgroundwater 102. For example, the reactor 145 may be house or otherwiseinclude an actinic radiation source and may be configured as an actinicradiation reactor as discussed above.

One or more lamps can be utilized in the reactor 145 to illuminate orirradiate the fluid contained therein. Particular embodiments caninvolve one or more reactors having a plurality of lamps, eachadvantageously disposed or positioned therein to irradiate the waterwith one or more illumination intensity levels for one or a plurality ofillumination periods. Further aspects can involve utilizing the one ormore lamps within any of the reactors in configurations that accommodateor facilitate a plurality of simultaneous illumination intensities.

The ultraviolet lamps can be advantageously positioned or distributedwithin the one or more reactors of the system to irradiate or otherwiseprovide actinic radiation to the water as desired. In certainembodiments, it is desired to distribute the lamps within the one ormore reactors to evenly distribute actinic radiation throughout thereactor. In any of systems 100A and 100B, the ultraviolet lamps can beadjusted to provide illumination at various intensities or various powerlevels. For example, ultraviolet lamps can be used that can be adjustedto operate at a plurality of illumination modes, such as dim, rated, andboost mode, for example, a low, medium, or high mode.

The one or more lamps can be positioned within the one or more actinicradiation reactors by being placed within one or more sleeves or tubeswithin the reactor. The tubes can hold the lamps in place and protectthe lamps from the water within the reactor. The tubes can be made ofany material that is not substantially degraded by the actinic radiationand the water or components of the water within the reactor, whileallowing the radiation to pass through the material. The tubes can havea cross-sectional area that is circular. In certain embodiments, thetubes can be cylindrical, and the material of construction thereof canbe quartz. Each of the tubes can be the same or different shape or sizeas one or more other tubes. The tubes can be arranged within the reactorin various configurations, for example, the sleeves may extend across aportion of or the entire length or width of the reactor. The tubes canalso extend across an inner volume of the reactor.

Commercially available ultraviolet lamps and/or quartz sleeves may beobtained from Hanovia Specialty Lighting, Fairfield, N.J., EngineeredTreatment Systems, LLC (ETS), Beaver Dam, Wis., and Heraeus NoblelightGmbH of Hanau, Germany. The quartz material selected can be based atleast in part on the particular wavelength or wavelengths that will beused in the process. The quartz material may be selected to minimize theenergy requirements of the ultraviolet lamps at one or more wavelengths.The composition of the quartz can be selected to provide a desired orsuitable transmittance of ultraviolet light to the water in the reactorand/or to maintain a desired or adequate level of transmissivity ofultraviolet light to the water. In certain embodiments, thetransmissivity can be at least about 50% for a predetermined period oftime. For example, the transmissivity can be about 80% or greater for apredetermined period of time. In certain embodiments, the transmissivitycan be in a range of about 80% to 90% for about 6 months to about oneyear. In certain embodiments, the transmissivity can be in a range ofabout 80% to 90% for up to about two years.

The tubes can be sealed at each end so as to not allow the contents ofthe reactor from entering the sleeves or tubes. The tubes can be securedwithin the reactor so that they remain in place throughout the use ofthe reactor. In certain embodiments, the tubes are secured to the wallof the reactor. The tubes can be secured to the wall through use of asuitable mechanical technique, or other conventional techniques forsecuring objects to one another. The materials used in the securing ofthe tubes is preferably inert and will not interfere with the operationof the reactor or negatively impact the purity of the water, or releasecontaminants to the water. The lamps can be arranged within the reactorsuch that they are parallel to each other. The lamps can also bearranged within the reactor at various angles to one another. Forexample, in certain embodiments, the lamps can be arranged to illuminatepaths or coverage regions that form an angle of approximately 90 degreessuch that they are approximately orthogonal or perpendicular to oneanother. The lamps can be arranged in this fashion, such that they forman approximately 90 degree angle on a vertical axis or a horizontalaxis, or any axis therebetween.

In certain embodiments, the reactor can comprise an array of tubes inthe reactor or vessel comprising a first set of parallel tubes and asecond set of parallel tubes. Each tube may comprise at least oneultraviolet lamp and each of the parallel tubes of the first set can bearranged to be at a desired angle relative to the second set of paralleltubes. The angle may be approximately 90 degrees in certain embodiments.The tubes of any one or both of the first array and the second array mayextend across an inner volume of the reactor. The tubes of the first setand the second set can be arranged at approximately the same elevationwithin the reactor.

Further configurations can involve tubes and/or lamps that are disposedto provide a uniform level of intensity at respective occupied orcoverage regions in the reactor. Further configurations can involveequispacially arranged tubes with one or more lamps therein.

The reactor may contain one or more arrays of tubes arranged within thereactor or vessel. A second array of tubes can comprise a third set ofparallel tubes, and a fourth set of parallel tubes orthogonal to thethird set of parallel tubes, each tube comprising at least oneultraviolet lamp. The fourth set of parallel tubes can also beorthogonal to at least one of the second set of parallel tubes and thefirst set of parallel tubes.

In certain embodiments, each array within the reactor or vessel can bepositioned a predetermined distance or elevation from another arraywithin the reactor. The predetermined distance between a set of twoarrays can be the same or different.

FIG. 9 exemplarily shows a cross-sectional view of a reactor vessel 300that can be used in system 100B. Reactor vessel 300 typically comprisesinlet 310, outlet 320, and baffle 315 which divides reactor vessel 300into upper chamber 325 and lower chamber 330. Reactor vessel 300 canalso comprise manifold 305 which can be configured to distribute waterintroduced through inlet 310 throughout the vessel. In certainembodiments, manifold 305 can be configured to evenly distribute waterthroughout the vessel. For example, manifold 305 can be configured toevenly distribute water throughout the vessel such that the reactoroperates as a plug flow reactor.

In some embodiments, the reactor vessel may comprise more than onebaffle 315 to divide the reactor vessel into more than two chambers.Baffle 315 can be used to provide mixing or turbulence to the reactor.In certain embodiments, as shown in FIG. 9, reactor inlet 310 is influid communication with lower chamber 330 and reactor outlet 320 is influid communication with upper chamber 325.

In some embodiments, at least three reactor chambers, each having atleast one ultraviolet (UV) lamp disposed to irradiate the water in therespective chambers with light of about or ranging from about 185 nm toabout 254 nm, 220 nm, and/or 254 nm at a desired or at various powerlevels, are serially arranged in reactor 120.

The reactor vessel can also comprise a plurality of ultraviolet lampspositioned within tubes, for example tubes 335 a-c and 340 a-c. In oneembodiment, as shown in FIG. 9, reactor vessel 300 comprises a first setof parallel tubes, tubes 335 a-c and a second set of parallel tubes (notshown). Each set of parallel tubes of the first set is approximatelyorthogonal to the second set to form first array 345. Tubes 335 a-c andthe second set of parallel tubes are at approximately the same elevationin reactor vessel 300, relative to one another.

Further, the reactor vessel can comprise a third set of parallel tubesand a fourth set of parallel tubes. Each set of parallel tubes of thefirst set is approximately orthogonal to the second set to form, forexample, second array 350. As exemplarily illustrated, tubes 340 a-c andthe second set of parallel tubes are at approximately the same elevationin reactor vessel 300, relative to one another. As shown in FIG. 9,first array 345 can be positioned at a predetermined distance fromsecond array 350. Vessel 300 can additionally comprise third array 355and fourth array 360, each optionally having similar configurations asfirst array 340 and second array 345. In another embodiment, a firsttube 335 b can be arranged orthogonal to a second tube 340 b to form afirst array. Additionally, a set of tubes, tube 365 a and tube 365 b canbe arranged orthogonal to another set of tubes, tube 370 a and tube 370b to form a second array. The position of the lamps of the second arrayare shown in FIG. 10A, including lamps 414, 420, 422, and 424. Thepositions of the lamps in the first array and the second array are shownin FIG. 10B, including lamps 426 and 428 of the first array and lamps414, 420, 422, and 424 of the second array.

The lamps can generate a pattern, depending on various properties of thelamp, including the dimensions, intensity, and power delivered to thelamp. The light pattern generated by the lamp is the general volume ofspace to which that the lamp emits light. In certain embodiments thelight pattern or illumination volume is defined as the area or volume ofspace that the lamp can irradiate or otherwise provide actinic radiationto and allow for oxidation of the recalcitrant organic contaminant.

As shown in FIGS. 10A and 10B, which shows exemplarily cross-sectionalviews of reactor 400 in which a first set of tubes 410 a-c are arrangedparallel to one another, and a second set of tubes 412 a-c are arrangedparallel to one another. As shown, first set of tubes 410 a-c isarranged orthogonal relative to second set of tubes 412 a-c. Lamps, suchas lamps 414, are dispersed within tubes 410 a-c and 412 a-c, and whenilluminated, can generate light pattern 416. One or more ultravioletlamps, or a set of lamps, can be characterized as projecting actinicradiation parallel an illumination vector. The illumination vector canbe defined as a direction in which one or more lamps emits actinicradiation. In an exemplarily embodiment, as shown in FIG. 10A, a firstset of lamps, including lamp 420 and 422, is disposed to project actinicradiation parallel to illumination vector 418.

A first set of ultraviolet lamps each of which is disposed to projectactinic radiation parallel a first illumination vector can be energized.A second set of ultraviolet lamps each of which is disposed to projectactinic radiation parallel a second illumination vector can also beenergized. At least one of the direction of the illumination and theintensity of at least one of the first set of ultraviolet lamps andsecond set of ultraviolet lamps can be adjusted. Each set of ultravioletlamps can comprise one or more ultraviolet lamps.

The number of lamps utilized or energized and the configuration of thelamps in use can be selected based on the particular operatingconditions or requirements of the system. For example, the number oflamps utilized for a particular process can be selected and controlledbased on characteristics or measured or calculated parameters of thesystem. For example measured parameters of the inlet water or treatedwater can include any one or more of TOC concentration, temperature, andflow rate. The number of energized lamps can also be selected andcontrolled based on the concentration or amount of persulfate added tothe system. For example, 12 lamps in a particular configuration can beused if the flow rate of the water to be treated is at or below acertain threshold value, for example a nominal or design flow rate, suchas 1300 gpm, while more lamps can be used if the flow rate of the waterto be treated rises above the threshold value. For example, if the flowrate increases from 1300 gpm to a selected higher threshold value,additional lamps can be energized. For example, 24 lamps may be used ifthe flow rate of the water to be treated reaches 1900 gpm. Thus the flowrate of the water can be partially determinative of which lamps and/orthe number of energized lamps in each reactor.

Contaminated groundwater 102 may thus enter the reactor 145, where itcomes into contact with a source of persulfate 115 and is exposed to thesource of actinic radiation. This treated water exits the reactor 145 asthe second treated aqueous solution 106. Thus, the first treated aqueoussolution 104 generated by the source of persulfate 115 in system 100A ispresent in the reactor 145 of system 100B.

Reactor 145 may be a plug flow reactor or a continuously stirred tankreactor, or combinations thereof. In certain embodiments, a plug flowreactor can be used to prevent the likelihood of blinded or regions oflower irradiation intensity, such as short circuiting, of illuminationby the lamps within the reactor. A plug flow reactor can be defined as areactor that operates under conditions that facilitate laminar flowpaths of fluid through the reactor, having parallel, non-turbulent flowpaths. Reactor 145 may be sized to provide a residence time sufficientto allow the persulfate and actinic radiation source degrade orotherwise convert the recalcitrant organic contaminants into one or moreinert compounds.

The reactor 145 may additionally be sized based on the expected flowrate of the system to provide a sufficient or a desired residence timein the reactor. In certain embodiments, the flow rate of water throughthe system can be based on the demand for treated water downstream ofthe system, or the flow rate of water being utilized upstream of thesystem, or both. In certain examples, the flow rate of water through thesystem, or through each reactor, can be between about 1 gallon perminute (gpm) and 3200 gpm. As will be appreciated, the flow rate willdepend on a variety of factors, including the application, the size ofthe system, and the type of contaminant being treated. The flow rate mayalso depend on other factors included in the system, such as thetemperature of a reactor housing the source of UV light. For instance,the flow rate may be increased so as to not have the reactor overheat.Further, the reactor and other unit operations and equipment of thesystem, such as pumps and flow valves, can be selected and sized toallow for fluctuations or changes in flow rates.

The reactor 145 may include a single chamber or may be divided into oneor more chambers by one or more baffles between the chambers. The bafflecan be used to provide mixing or turbulence to the reactor or preventmixing or promote laminar, parallel flow paths through the interior ofthe reactor, such as in the one or more chambers. In certain instances,a reactor inlet may be in fluid communication with a first chamber and areactor outlet may be in fluid communication with a second chamber.

According to at least one embodiment, the reactor 145 includes a singlechamber having at least one UV lamp disposed to irradiate thecontaminated groundwater with light of 185 nm, 220 nm, or 254 nm, orranging from about 185 nm to about 254 nm. According to otherembodiments, the reactor 145 is divided into multiple chambers. Forexample, according to some embodiments, at least three reactor chambersare serially arranged in reactor 145, each having at least oneultraviolet (UV) lamp disposed to irradiate the water in the respectivechambers with light of about 185 nm, 220 nm, and/or 254 nm, or rangingfrom about 185 nm to about 254 nm, at various power levels. According toother embodiments, sets of serially arranged reactors may be arranged inparallel. For example, a first set of reactors in series may be placedin parallel with a second set of reactors in series, with each sethaving three reactors, for a total of six reactors. Any one or more ofthe reactors in each set may be in service at any time. In certainembodiments, all reactors may be in service, while in other embodiments,only one set of reactors is in service.

In a similar manner as discussed above with respect to FIG. 1A, inaccordance with some embodiments, the controller 150 of system 100B may,for example, receive an indication of a flow rate and/or a TOCconcentration or level and generate and transmit a drive signal to thesource of persulfate 115 and/or the source actinic radiation housedwithin the reactor, for example, to adjust a rate at which thepersulfate is introduced to the reactor 145, or adjust the dose ofirradiation dispensed by the actinic radiation source. As noted above,the drive signal may be based on the one or more input signals and atarget or predetermined value or set-point, or threshold value. Forexample, if the input signal that provides a representation of the TOCvalue of the contaminated groundwater 102 or second treated aqueousstream 106 is above the target TOC value or threshold value, or a rangeof acceptable TOC values, i. e., a tolerance range, then the drivesignal can be generated to adjust the rate of persulfate 115 introducedto the reactor 145 and/or dose administered by the actinic radiationsource, such as by adjusting at least one of the lamp configuration andthe lamp intensity. In some embodiments, the controller 150 may alsoreceive an indication of a persulfate amount or rate of addition, andgenerate and transmit a drive signal to reactor 145, a drive signal tothe source of persulfate 115, and/or the actinic radiation source inresponse to the input signal associated with the persulfate amount, suchas the persulfate concentration in one or more of the water streams ofthe system. According to some embodiments, the controller 150 maygenerate and transmit control signals to, for example, energize oradjust an intensity or power of output radiation emitted by the actinicradiation source within the reactor 145. Thus, depending on the amountor rate of addition of persulfate 115 and/or the level of TOC in thecontaminated groundwater 102, the control signal may be increased ordecreased appropriately, incrementally, or proportionally.

As discussed above, the controller 150 may be configured in a feedbackarrangement and thus may be configured to generate and transmit one ormore control signals to any one of the source of persulfate 115, actinicradiation source within the reactor 145, and/or the reactor 145 itself.For instance, the TOC value or the resistivity, or both, of the secondtreated aqueous solution 106 may be utilized to generate control signalsto any of contaminated groundwater 102 and reactor 145. For instance,control signals to the reactor 145 may include control signals to thesource of actinic radiation and/or to valves that allows water to enterand exit the reactor 145. Similarly to system 100A, a portion of thesecond treated aqueous solution 106 may be recirculated based on ameasured TOC value taken from the second treated aqueous solution.

Another embodiment, indicated generally at 500A, is provided in FIG. 11.The system 500A includes source of contaminated groundwater 502, sourceof persulfate 515, irradiation source 525, and associated fluid conduits504 and 506, which are similar in structure and function to elements ofthe systems illustrated in FIGS. 1A and 1B. The pretreatment unit 510 ofsystem 500A is capable of removing iron from an aqueous solution. InFIG. 11, the pretreatment unit 510 is capable and configured to removeiron from the contaminated groundwater 502. The source of persulfate 505is fluidly connected downstream from the pretreatment subsystem 510 suchthat pretreated groundwater travels through conduit 503 from thepretreatment subsystem 510 to the source of persulfate 515.

The pretreatment subsystem 510 of system 500A includes media filter 512and a source of an oxidant 514. However, the pretreatment subsystem 510may include any unit configured to remove iron. The pretreatmentsubsystem may include one of the media filter 512 and the source of theoxidant 514.

The water treatment system 500A may include recirculation line 506extending between a point downstream from the irradiation source 525 anda point upstream from the source of persulfate 515. As shown in FIG. 11,the recirculation line 506 may extend to a point upstream from thepretreatment subsystem 510. In other embodiments, the recirculation linemay extend to a point between pretreatment subsystem 510 and source ofpersulfate 515.

Another embodiment, indicated generally at 500B, is provided in FIG. 12.The system 500B includes source of contaminated groundwater 502, sourceof persulfate 515, irradiation source 525, and associated fluid conduits504 and 506, which are similar in structure and function to elements ofthe systems illustrated in FIG. 11. System 500B includes pretreatmentsubsystem 516 positioned upstream from the source of persulfate 515. Thepretreatment subsystem 516 may be configured to produce high puritywater for the source of persulfate 515. The pretreatment subsystem 516may comprise a water purification unit configured to produce the highpurity water. The water purification unit may be, for example, an ionexchange unit or a reverse osmosis unit, as previously described.Additionally or alternatively, the pretreatment subsystem 516 may becapable and configured to remove iron from a source of makeup water forthe source of persulfate 516.

Another embodiment, indicated generally at 500C, is provided in FIG. 13.The system 500C includes source of contaminated groundwater 502, sourceof persulfate 515, irradiation source 525, pretreatment subsystem 510,pretreatment subsystem 516, and associated fluid conduits 503, 504, and506, which are similar in structure and function to elements of thesystems illustrated in FIGS. 11 and 12. System 500C further includescontroller 550 which is similar in structure and function to controller150, described above with reference to FIGS. 1A and 1B. Controller 550may be operatively connected to one or more elements of the system aspreviously described and to sensor 530 c configured to measure aconcentration of iron in the contaminated groundwater.

According to a further embodiment, the treatment systems disclosedherein may include a sensor that is configured to measure theconcentration of persulfate. According to yet a further embodiment, thesystem may include a sensor that is configured to measure theconcentration of a specific recalcitrant organic contaminant. Forexample, if the groundwater contains a halogenated contaminant, thesensor may be configured to detect the presence of the halogen. Othertypes of sensors are also within the scope of this disclosure.

Although not explicitly shown, the systems may further include one ormore flow control devices, such as valves, regulators, pipes or otherconduits, connectors, and weirs.

According to at least one embodiment, the systems disclosed herein, maybe a mobile-based platform. The mobile-based system may be scalable,modular, and portable, which allows the system to be customizedaccording to the site-specific remediation requirements. Themobile-based platform may be designed to be both transported andoperated from mobile platforms that may be moved between sites andon-site. Multiple systems may also be used, in series or in parallel,depending on the remediation needs at the site. In certain instances themobile-based platform may be designed and sized to fit standard sizedshipping containers, or may be designed and sized to a custom enclosureor platform such as a skid or trailer that is able to be driven fromlocation to location.

EXAMPLES

The systems and methods described herein will be further illustratedthrough the following examples, which are illustrating in nature and arenot intended to limit the scope of the disclosure.

Example 1—Removal of 1,4-Dioxane Using Persulfate and UV Light

FIG. 2 schematically illustrates a system 200 in accordance with one ormore aspects, and within the context of the examples discussed below,illustrates a test set-up used to perform a series of experiments totest the effectiveness of ammonium persulfate and UV light on reducingconcentrations of dioxane in water. The system 200 as shown in FIG. 2included a tank 205, a pump 207, a chiller 235 for controllingtemperature and to keep the UV source 225 from overheating, an in-linemixer 220 for mixing the contaminated water with the source ofpersulfate 215, a UV source 225 having a wavelength in a range from 185nm to about 254 nm, chemical injection means for introducing a source ofammonium persulfate (APS) 215, two mixed bed deionizers 210 a and 210 bthat function to remove unwanted ionic species, a Total Organic Carbon(TOC) analyzer 230, and multiple sensors, including pressure sensors 240a and 240 b, flow meter 242, and conductivity sensor 244). System 200 isanalogous to system 100A shown in FIG. 1A in that the source ofpersulfate 215 and the exposure to the UV source 225 are performedsequentially. For example, the persulfate 215 may be introduced to watercontaining contaminant 202 to produce a first treated aqueous solution204, which may exposed to the source of UV light 225 to produce a secondtreated aqueous solution 206.

Although not specifically shown, aspects may include a controller thatis configured to generate and transmit a control signal that adjusts arate of heat transfer in chiller 235 based on, for example, an inputsignal from one or more sensors positioned within the system, such as asensor positioned at an outlet of the pump 207. The control signal mayincrease or decrease the flow rate and/or the temperature of the coolingfluid introduced into the chiller 235 to provide water at a desired orpredetermined temperature.

A controller may also generate and transmit a control signal thatenergizes pump 207 or adjusts a flow rate of the water flowingtherethrough. For instance, if the pump utilizes a variable frequencydrive, the control signal can be generated to appropriately adjust thepump motor activity level to achieve a target flow rate value. A pumpmay also be used to adjust the flow rate of the source of persulfate215. Alternatively, an actuation signal may actuate a valve thatregulates a rate of flow of the water exiting from pump 207, theproportion and/or flow rate of second treated aqueous stream 206 that isrecycled back to tank 207, and the flow rate of the source of persulfate215.

For this experiment, uncontaminated RO water was supplied having <10 ppbTOC. The hydraulic retention time (HRT) associated with the source of UV225 was calculated using Equations 5 and 6 below using the parameterslisted in Table 2 and modeling the lamp sleeve and reactor as acylinder.

TABLE 2 UV Lamp Sleeve Dimensions UV Reactor Dimensions Diameter = 1.62inches Diameter = 12 inches Length = 42 inches Length = 42 inches Volumeof Lamp Sleeve = 86.53 in³ Volume of Reactor = 4747.69 in³ Reactor flowrate = 7 gal/min (0.03 m³/min)

$\begin{matrix}\begin{matrix}{{{Net}\mspace{14mu}{Volume}\mspace{14mu}{of}\mspace{14mu}{Reactor}} = {{{Volume}\mspace{14mu}{of}\mspace{14mu}{Reactor}} -}} \\{{Volume}\mspace{14mu}{of}\mspace{14mu}{Lamp}\mspace{14mu}{Sleeves}} \\{= {4574.63\mspace{14mu}{{in}^{3}\left( {0.07\mspace{14mu} m^{3}} \right)}}}\end{matrix} & {{Equation}\mspace{14mu} 5} \\{\mspace{79mu}\begin{matrix}{{HRT} = {{Volume}\mspace{14mu}{of}\mspace{14mu}{{Reactor}/{Flow}}\mspace{14mu}{rate}}} \\{= {2.83\mspace{14mu}{minutes}}}\end{matrix}} & {{Equation}\mspace{14mu} 6}\end{matrix}$

As noted above, the source of water was uncontaminated RO having <10 ppbTOC. This water was placed in the tank 205 and recirculated withoutpersulfate 215 addition and with UV light 225 to obtain a baseline TOC.The UV light was turned off and 1,4-dioxane added and the TOCmeasurements were allowed to stabilize. The UV light 225 was turned onand the water was directed to drain. TOC measurements were performed todetermine the effect of UV on 1,4-dioxane prior to the addition ofammonium persulfate (APS). APS was then added prior to the UV light andTOC measurements were performed. The results of the three tests areshown in FIGS. 3-5, respectively, under various test conditions and1,4-dioxane concentrations. The test conditions, 1,4-dioxaneconcentrations, and results are summarized below in Tables 3-5. Data wascollected for four concentration levels (T1, T2, T3, T4) of APSinjection.

TABLE 3 Test 1 conditions and results for FIG. 3 Baseline TOC = 2.89 ppbDioxane concentration (C_(i)) = 29.23 ppb TOC in (TOC_(i)) = 32.12 ppbUV flowrate = 7 gpm (except at T3 = 10 gpm) UV Lamp kW = 2.3, 2 lamps UVdose = 10.95 kWh/1000 gallons (except at T4 = 7.67 kWh/1000 gallons) T1APS = 0 ppm, T2 APS = 3 ppm, T3 APS = 6 ppm, T4 APS = 6 ppm TOC DioxaneAPS out % TOC log Out (C_(o)) % Dioxane ratio (TOC_(o)) destructionTOC_(i)/TOC_(o) (ppb) destruction EE/O T1 0 3.63 88.7 0.95 0.74 97 11.6T2  93:1 2.75 91.4 1.07 −0.14 100 10.3 T3 187:1 2.77 91.4 1.06 −0.12 10010.3 T4 187:1 2.58 92.0 1.10 −0.31 100 7

The Electrical Energy per Order (EE/O) is a scale-up parameter and is ameasure of the treatment obtained in a fixed volume of water as afunction of exposure to UV light. EE/O is defined as the kilowatt hoursof electricity required to reduce the concentration of a compound in1000 gallons by one order of magnitude (or 90%). The unit for EE/O iskWh/1000 gallons/order (The UV/Oxidation Handbook, SolarchemEnvironmental Systems, Chapter 4, 1994). The linear relationship betweenthe UV dose and the log of contaminant concentration implies that asingle EE/O may completely describe the UV treatment characteristics ofa contaminant. Thus, the lower the EE/O, the more efficient thetreatment. The relationship also implies that it takes the same amountof energy to treat the first 90% of the contaminant as it does to treatthe subsequent 90% of the remaining contaminant. UV treatment istherefore very efficient at reducing the mass loading of a contaminantand in certain instances may be used as a cost-effective pretreatmentstep.

The EE/O measured in a design test is specific to the water tested andto the compound of interest, and it will vary for differentapplications. Typical EE/O values for a range of organic contaminantsare provided below in Table A. EE/O may make the scale-up and comparisonof relative treatment performance a simple process. With the EE/Odetermined, either through design tests or estimated by using Table A, aUV dose required in a specific case may be calculated according toEquation 7:UV Dose=EE/O×log(C _(i) /C _(f))  Equation 7:where C_(i) is the initial concentration, and C_(f) is the anticipatedor required discharge standard. For streams with several contaminants,the required energy is not additive but determined by the contaminantrequiring the greatest UV dose.

TABLE A Typical EE/O values for contaminant destruction Contaminant EE/O(kWh/1000 USgal/order) 1,4-dioxane 2-6 atrazine 30 benzene 2-5chlorobenzene  5 DCE 2-5 NDMA 2-5 PCE 3-8 PCP 10 phenol  5 TCE 2-4toluene 2-5 xylene 2-5 vinyl chloride 2-3

TABLE 4 Test 2 conditions and results for FIG. 4 Baseline TOC = 2.21 ppbDioxane concentration (C_(i)) = 293.79 ppb TOC in (TOC_(i)) = 296 UVflowrate = 7 gpm UV Lamp kW = 2.3, 2 lamps UV dose = 10.95 kWh/1000gallons T1 APS = 0 ppm, T2 APS = 3 ppm, T3 APS = 15 ppm TOC Dioxane APSout % TOC log Out (C_(o)) % Dioxane ratio (TOC_(o)) destructionTOC_(i)/TOC_(o) (ppb) destruction EE/O T1 0 84 71.6 0.55 81.79 72 20.0T2 10:1 18.5 93.8 1.20 16.29 95 9.1 T3 50:1 0.5 99.8 2.77 −1.71 100 4.0

TABLE 5 Test 3 conditions and results for FIG. 5 Baseline TOC = 2.39 ppbDioxane concentration (C_(i)) = 293.61 ppb TOC in (TOC_(i)) = 296 UVflowrate = 7 gpm UV Lamp kW = 2.3, 1 lamp UV dose = 5.48 kWh/1000gallons T1 APS = 0 ppm, T2 APS = 3 ppm, T3 APS = 15 ppm, T4 APS = 30 ppmTOC Dioxane APS out % TOC log Out (C_(o)) % Dioxane ratio (TOC_(o))destruction TOC_(i)/TOC_(o) (ppb) destruction EE/O T1 0 196.3 33.7 0.18193.91 34 30.7 T2 10.1 96.4 67.4 0.49 94.01 68 11.2 T3 50:1 6.6 97.81.65 4.21 99 3.3 T4 100:1  1.89 99.4 2.19 −0.50 100 2.5

The results indicate that it is possible to essentially remove all ofthe 1,4-dioxane when using a combination of persulfate and UV light. Theresults also indicate that persulfate and UV light is effective atremoving both lower (30 ppb) and higher (300 ppb) concentrations ofdioxane from contaminated water and concentration values of APS as lowas 3 ppm were effective at lowering the concentration of dioxane. Priorattempts to treat dioxane and other organic contaminants have includedin-situ injection methods of persulfate without the use of UV and werenot nearly as effective as the ex-situ methods and systems disclosedherein.

Example 2—Destruction of TOC for Various Contaminants

An experiment was conducted to test the effectiveness of using UV lightalone versus using persulfate in combination with UV light in reducingthe concentration of 10 different organic contaminants (includingdioxane) in water. Most of the listed organics in Table 6 arerecalcitrant organic contaminants.

The test was set up according to a system set up as a 1.5 m³/h pilotapparatus and was similar to system 200 shown in FIG. 2. The flow ratewas about 1-2 m³/h and the UV source 225 contained two medium pressurelamps operated at a lamp power of 3.5 kW each and at the same wavelengthas used in Example 1. RO water was processed by a mixed bed deionizer toprovide source water having <10 ppb TOC. This water was placed in thetank 205 and recirculated at a rate of 10 gpm without persulfate 215(APS) addition and with UV light 225 to obtain a baseline TOC of 2-3ppb. The UV light was then turned off and the target contaminant wasadded and the TOC measurements were allowed to stabilize. The UV light225 was turned on and the flow rate was reduced to 1.6 m³/h and thewater was directed to drain. TOC measurements were made with and withoutAPS injection. The results shown in Tables 6 and 7 below show theresults of the test and reflect the effect on TOC levels when UV is usedalone versus when persulfate is used in combination with UV. FIG. 6graphically displays the results obtained from urea, and FIG. 7graphically displays the results from 1,4-dioxane.

TABLE 6 Contaminant concentrations and results % TOC DestructionContaminant Feed ppb UV only UV + APS atrazine 25 70 99 carbaryl 29 95100 chloroform 29 97 100 formic acid 30 100 — 1,4-dioxane 296 72 100humic acid 33 90 99 IPA 30 77 100 starch 33 94 100 tryptophan 29 94 100urea 21 9 100

TABLE 7 IPA concentrations and results Contaminant: IPA % TOCDestruction Feed IPA ppb UV only UV + APS 100 84 100 250 61 100 500 34100 1000 15 100

The results indicate that in just over half the contaminants, nearlycomplete (99-100%) destruction of the organic species was accomplishedby exposure to UV light alone. Urea showed the lowest reduction, withless than 10% destruction achieved using only UV. However, nearlycomplete destruction (99-100%) was achieved for all the contaminants byusing persulfate in combination with UV light in a single pass. Thus,EPA or other regulatory standards for contaminants can be met using theex-situ methods and systems disclosed herein in a single pass.

Example 3—Destruction of TOC for Various Recalcitrant OrganicContaminants

A second experiment was conducted to test the effectiveness of using UVlight alone versus using persulfate in combination with UV light inreducing the concentration of three different recalcitrant organiccontaminants (including dioxane) in water. A test apparatus similar tothe one used in Example 2 and as exemplified in FIG. 2 was used toperform these experiments, and the same procedure was followed. Thesource water used in this experiment had a background alkalinity of 300ppm, and the persulfate used in this case was sodium persulfate (SPS).Table 8 below summarizes the results of the test and reflect the effecton TOC levels when UV is used alone versus when persulfate is used incombination with UV for the three recalcitrant organic contaminants thatwere tested.

TABLE 8 Contaminant concentrations and results Initial Sodium % TOCDestruction Recalcitrant organic TOC persulfate/ UV + sodium contaminantppb TOC UV only persulfate 1,4-dioxane 300 100 73 99 1,2-dichloroethane300 100 39.5 73 trichloroethylene 300 0 >99.9

The results indicate that nearly complete destruction of TOC using UValone was only exhibited for trichloroethylene. Nearly completedestruction of TOC for dioxane was observed. A lower flowrate and/or ahigher persulfate ratio may increase the destruction of TOC for the1,2-dichloroethane.

Prophetic Example 1—Effect of Removal of Iron from Feed Stream onRemoval of Contaminants

Contaminated groundwater may be pretreated before introduction of apersulfate solution. The contaminated groundwater may have an ironconcentration of about 10 mg/L. The iron concentration may be reduced byabout 99% before being combined with a persulfate solution. Thecontaminated groundwater may then be treated by the methods disclosedherein. The contaminated groundwater may have a final concentration of1,4-dioxane of less than 1 ppb. Accordingly, the pretreatment operationdisclosed herein may enhance removal of recalcitrant organiccontaminates, such as 1,4-dioxane, from contaminated groundwater.

Prophetic Example 2—Effect of Removal of Iron from Feed Stream UV QuartzSleeve Maintenance

Contaminated groundwater may be pretreated before introduction of apersulfate solution. The contaminated groundwater may have an ironconcentration of about 10 mg/L. The iron concentration may be reduced byabout 99% before being combined with a persulfate solution. Thecontaminated groundwater may then be treated by the methods disclosedherein. With the removal of iron from the contaminated groundwater, theUV lamp quartz sleeve may foul at a slower rate. The UV lamp quartzsleeve may be operated for twice as long before the fouling adverselyaffects the system. Accordingly, the pretreatment operation disclosedherein may improve operation of the wastewater treatment system byreducing downtime.

The systems and methods disclosed herein are thus capable of completelyremoving recalcitrant organic contaminant from groundwater using anex-situ method and system in a single pass. The results also indicatethat the systems and methods are capable of handling backgroundalkalinity, i. e., groundwater having various levels of alkalinity.Alkaline components and other reaction products may have the potentialto interfere with the reaction of persulfate with the contaminant. Theseresults indicate that these potential side reactions did not interferewith the effectiveness of the TOC removal.

The aspects disclosed herein are not limited in their application to thedetails of construction and the arrangement of components set forth inthe following description or illustrated in the accompanying drawings.These aspects are capable of assuming other embodiments and of beingpracticed or of being carried out in various ways. Examples of specificimplementations are provided herein for illustrative purposes only andare not intended to be limiting. In particular, acts, components,elements, and features discussed in connection with any one or moreembodiments are not intended to be excluded from a similar role in anyother embodiments.

Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. Any references toexamples, embodiments, components, elements or acts of the systems andmethods herein referred to in the singular may also embrace embodimentsincluding a plurality, and any references in plural to any embodiment,component, element or act herein may also embrace embodiments includingonly a singularity. References in the singular or plural form are notintended to limit the presently disclosed systems or methods, theircomponents, acts, or elements. The use herein of “including,”“comprising,” “having,” “containing,” “involving,” and variationsthereof is meant to encompass the items listed thereafter andequivalents thereof as well as additional items. References to “or” maybe construed as inclusive so that any terms described using “or” mayindicate any of a single, more than one, and all of the described terms.In addition, in the event of inconsistent usages of terms between thisdocument and documents incorporated herein by reference, the term usagein the incorporated reference is supplementary to that of this document;for irreconcilable inconsistencies, the term usage in this documentcontrols. Moreover, titles or subtitles may be used in the specificationfor the convenience of a reader, which shall have no influence on thescope.

Having thus described several aspects of at least one example, it is tobe appreciated that various alterations, modifications, and improvementswill readily occur to those skilled in the art.

For instance, examples disclosed herein may also be used in othercontexts. Such alterations, modifications, and improvements are intendedto be part of this disclosure, and are intended to be within the scopeof the examples discussed herein. Accordingly, the foregoing descriptionand drawings are by way of example only.

What is claimed is:
 1. A system for treating contaminated groundwater,comprising: a pretreatment subsystem capable of removing iron from anaqueous solution; a source of persulfate fluidly connectable to a sourceof contaminated groundwater having an initial concentration of arecalcitrant organic contaminant, the source of persulfate fluidlyconnected downstream from the pretreatment subsystem and configured tointroduce the persulfate to the contaminated groundwater and produce afirst treated aqueous solution; and an irradiation source fluidlyconnected downstream from the source of persulfate, the irradiationsource configured to irradiate the first treated aqueous solution andproduce a second treated aqueous solution having a concentration of therecalcitrant organic contaminant lower than the initial concentration ofthe recalcitrant organic contaminant.
 2. The system of claim 1, whereinthe pretreatment subsystem is fluidly connectable downstream from thesource of contaminated groundwater and is configured to remove iron fromthe contaminated groundwater prior to introduction of the persulfate. 3.The system of claim 2, wherein the pretreatment subsystem comprises amedia filter.
 4. The system of claim 2, wherein the concentration ofiron downstream of the pretreatment subsystem is 0.1 mg/L or less. 5.The system of claim 2, wherein the pretreatment subsystem comprises asource of an oxidant.
 6. The system of claim 5, wherein the source ofthe oxidant comprises chlorine or an oxygen containing gas.
 7. Thesystem of claim 1, wherein the pretreatment subsystem comprises a waterpurification unit and is configured to produce high purity water for thesource of persulfate.
 8. The system of claim 7, wherein the waterpurification unit comprises an ion exchange unit or a reverse osmosisunit.
 9. The system of claim 1, further comprising a TOC concentrationsensor fluidly connected to the contaminated groundwater; and acontroller operably connected to the TOC concentration sensor andconfigured to control at least one of a rate at which the persulfate isintroduced to the contaminated groundwater and a dose of irradiationapplied by the irradiation source based on an output signal from the TOCconcentration sensor.
 10. The system of claim 1, wherein the system is amobile-based platform.
 11. The system of claim 1, further comprising apump configured to extract the contaminated groundwater from the sourceof contaminated groundwater.
 12. The system of claim 11, wherein thesource of contaminated groundwater is a remediation site.
 13. The systemof claim 1, wherein the irradiation source is configured to produce thesecond treated aqueous solution having a concentration of therecalcitrant organic contaminant that is at least 50% less than theinitial concentration of recalcitrant organic contaminant.
 14. Thesystem of claim 13, wherein the irradiation source is configured toproduce the second treated aqueous solution having a concentration ofthe recalcitrant organic contaminant that is at least 99% less than theinitial concentration of recalcitrant organic contaminant.
 15. Thesystem of claim 14, wherein the recalcitrant organic contaminant is1,4-dioxane and the irradiation source is configured to produce thesecond treated aqueous solution having a concentration of therecalcitrant organic contaminant of 1 ppb or less.
 16. The system ofclaim 1, further comprising a recirculation line extending between apoint downstream from the irradiation source and a point upstream fromthe source of persulfate.
 17. The system of claim 16, wherein the pointupstream from the source of persulfate is upstream from the pretreatmentsubsystem.
 18. A method of treating contaminated groundwater having aninitial concentration of a recalcitrant organic contaminant and aninitial concentration of iron, comprising: pretreating the contaminatedgroundwater to produce a pretreated groundwater having a concentrationof iron less than the initial concentration of iron; introducing apersulfate to the pretreated groundwater to produce a first treatedaqueous solution; and exposing the first treated aqueous solution toirradiation to produce a second treated aqueous solution having aconcentration of the recalcitrant organic contaminant that is at least50% less than the initial concentration of recalcitrant organiccontaminant, wherein the concentration of recalcitrant organiccontaminant in the second treated aqueous solution is at least 99% lessthan the initial concentration of contaminant, and wherein therecalcitrant organic contaminant is 1,4-dioxane and the concentration ofthe recalcitrant organic contaminant in the second treated aqueoussolution is 1 ppb or less.
 19. The method of claim 18, furthercomprising extracting the contaminated groundwater from a remediationsite.
 20. The method of claim 18, further comprising: measuring a totalorganic carbon (TOC) value of the contaminated groundwater to betreated; and adjusting at least one of a rate at which the persulfate isintroduced to the contaminated groundwater and a dose of the irradiationbased on the measured TOC value.